diff --git a/app/modules/project/templates/project/inbox.html b/app/modules/project/templates/project/inbox.html
index 2e66a3b..8c28ef9 100644
--- a/app/modules/project/templates/project/inbox.html
+++ b/app/modules/project/templates/project/inbox.html
@@ -1,7 +1,7 @@
 {% extends "erp_base.html" %}
 
 {% block head_extra %}
-<link rel="stylesheet" href="/static/project.css?v=20260625h" />
+<link rel="stylesheet" href="/static/project.css?v=20260625i" />
 <link rel="stylesheet" href="/static/vendor/material-symbols/material-symbols.css" />
 {% endblock %}
 
@@ -45,5 +45,5 @@
   {% endif %}
 </div>
 
-<script src="/static/project.js?v=20260625h" defer></script>
+<script src="/static/project.js?v=20260625i" defer></script>
 {% endblock %}
diff --git a/app/modules/project/templates/project/index.html b/app/modules/project/templates/project/index.html
index ae5c382..5980f41 100644
--- a/app/modules/project/templates/project/index.html
+++ b/app/modules/project/templates/project/index.html
@@ -1,7 +1,7 @@
 {% extends "erp_base.html" %}
 
 {% block head_extra %}
-<link rel="stylesheet" href="/static/project.css?v=20260625h" />
+<link rel="stylesheet" href="/static/project.css?v=20260625i" />
 <link rel="stylesheet" href="/static/vendor/material-symbols/material-symbols.css" />
 {% endblock %}
 
@@ -101,5 +101,5 @@
 <script>
   window.PJ_COLORS = {{ ["#4573d2","#37a3a3","#62a420","#e8a33d","#e8384f","#aa62e3","#f06a6a","#5a6772"] | tojson }};
 </script>
-<script src="/static/project.js?v=20260625h" defer></script>
+<script src="/static/project.js?v=20260625i" defer></script>
 {% endblock %}
diff --git a/app/modules/project/templates/project/project.html b/app/modules/project/templates/project/project.html
index be13afb..6a9d772 100644
--- a/app/modules/project/templates/project/project.html
+++ b/app/modules/project/templates/project/project.html
@@ -1,13 +1,49 @@
 {% extends "erp_base.html" %}
 
 {% block head_extra %}
-<link rel="stylesheet" href="/static/project.css?v=20260625h" />
+<link rel="stylesheet" href="/static/project.css?v=20260625i" />
 <!-- 구글 머티리얼 심볼(담당자 아이콘 등) — self-host -->
 <link rel="stylesheet" href="/static/vendor/material-symbols/material-symbols.css" />
 <!-- 타임라인 vis-timeline — self-host -->
 <link href="/static/vendor/vis-timeline/vis-timeline-graph2d.min.css" rel="stylesheet" />
 {% endblock %}
 
+{# ── 아사나식 프로젝트/서브프로젝트 재귀 트리 ── #}
+{% macro proj_tree(nodes, active_id, can_edit, depth) %}
+<ul class="pj-tree" {% if depth > 0 %}data-sub="1"{% endif %}>
+  {% for n in nodes %}
+  <li class="pj-tree-li" data-id="{{ n.id }}">
+    <div class="pj-tree-row {% if n.id == active_id %}is-active{% endif %}" style="--pj-indent: {{ depth }}">
+      {% if n.children %}
+      <button type="button" class="pj-tree-caret" aria-expanded="false" title="펼치기/접기">
+        <span class="material-symbols-outlined">chevron_right</span>
+      </button>
+      {% else %}
+      <span class="pj-tree-caret-spacer"></span>
+      {% endif %}
+      <a class="pj-tree-link" href="/project/p/{{ n.id }}">
+        <span class="pj-tree-icon material-symbols-outlined" style="color: {{ n.color }}">
+          {% if n.children %}folder{% else %}check_circle{% endif %}
+        </span>
+        <span class="pj-tree-name">{{ n.name }}</span>
+      </a>
+      {% if can_edit %}
+      <span class="pj-tree-acts">
+        <button type="button" class="pj-icon-btn pj-tree-addsub" data-id="{{ n.id }}" title="서브프로젝트 추가">+</button>
+        <button type="button" class="pj-icon-btn pj-tree-del" data-id="{{ n.id }}" data-name="{{ n.name }}" title="삭제">×</button>
+      </span>
+      {% endif %}
+    </div>
+    {% if n.children %}
+    <div class="pj-tree-children" hidden>
+      {{ proj_tree(n.children, active_id, can_edit, depth + 1) }}
+    </div>
+    {% endif %}
+  </li>
+  {% endfor %}
+</ul>
+{% endmacro %}
+
 {% block content %}
 <div class="pj-wrap pj-project-view"
      data-project-id="{{ project.id }}"
@@ -16,29 +52,20 @@
      data-me="{{ user.email }}">
 
   <div class="pj-layout">
-    <!-- ── 좌측: 서브프로젝트 + 멤버 ── -->
+    <!-- ── 좌측: 프로젝트 트리 + 멤버 ── -->
     <aside class="pj-side">
       <div class="pj-side-block">
         <div class="pj-side-head">
-          <span>서브프로젝트</span>
-          {% if can_manage %}
-          <button type="button" class="pj-icon-btn" id="pj-new-sub" title="서브프로젝트 추가">+</button>
+          <span>프로젝트</span>
+          {% if is_admin %}
+          <button type="button" class="pj-icon-btn" id="pj-new-project-side" title="새 프로젝트">+</button>
           {% endif %}
         </div>
-        <ul class="pj-sub-list" id="pj-sub-list">
-          {% for s in subprojects %}
-          <li>
-            <a href="/project/p/{{ s.id }}">
-              <span class="pj-sub-dot" style="background: {{ s.color }}"></span>{{ s.name }}
-            </a>
-            {% if can_manage %}
-            <button type="button" class="pj-icon-btn pj-del-sub" data-id="{{ s.id }}" title="삭제">×</button>
-            {% endif %}
-          </li>
-          {% else %}
-          <li class="pj-empty-sm">없음</li>
-          {% endfor %}
-        </ul>
+        {% if tree %}
+        {{ proj_tree(tree, project.id, (is_admin or can_manage), 0) }}
+        {% else %}
+        <div class="pj-empty-sm">프로젝트 없음</div>
+        {% endif %}
       </div>
 
       <div class="pj-side-block">
@@ -256,5 +283,5 @@
 </script>
 
 <script src="/static/vendor/vis-timeline/vis-timeline-graph2d.min.js"></script>
-<script src="/static/project.js?v=20260625h" defer></script>
+<script src="/static/project.js?v=20260625i" defer></script>
 {% endblock %}
diff --git a/app/static/project.css b/app/static/project.css
index c58ac7a..d1e61c3 100644
--- a/app/static/project.css
+++ b/app/static/project.css
@@ -60,13 +60,32 @@
 
 .pj-side-block { margin-bottom: 22px; }
 .pj-side-head { display: flex; align-items: center; justify-content: space-between; font-size: 12px; font-weight: 700; color: #6b7280; text-transform: uppercase; letter-spacing: .04em; margin-bottom: 8px; }
-.pj-sub-list, .pj-member-list { list-style: none; margin: 0; padding: 0; }
-.pj-sub-list li, .pj-member-list li { display: flex; align-items: center; gap: 8px; padding: 5px 4px; border-radius: 7px; }
-.pj-sub-list li:hover, .pj-member-list li:hover { background: #f6f7f8; }
-.pj-sub-list a { display: flex; align-items: center; gap: 8px; text-decoration: none; color: inherit; font-size: 13.5px; flex: 1; }
-.pj-sub-dot { width: 8px; height: 8px; border-radius: 50%; }
+.pj-member-list { list-style: none; margin: 0; padding: 0; }
+.pj-member-list li { display: flex; align-items: center; gap: 8px; padding: 5px 4px; border-radius: 7px; }
+.pj-member-list li:hover { background: #f6f7f8; }
 .pj-member-name { font-size: 13px; flex: 1; }
 
+/* ── 아사나식 프로젝트 트리 ── */
+.pj-tree { list-style: none; margin: 0; padding: 0; }
+.pj-tree .pj-tree { padding-left: 0; }   /* 들여쓰기는 row 패딩으로 처리 */
+.pj-tree-row { display: flex; align-items: center; gap: 2px; border-radius: 7px; padding-right: 2px;
+               padding-left: calc(var(--pj-indent, 0) * 16px); position: relative; }
+.pj-tree-row:hover { background: #f1f2f4; }
+.pj-tree-row.is-active { background: #ececf8; }
+.pj-tree-row.is-active .pj-tree-name { font-weight: 700; color: #1e1f21; }
+.pj-tree-caret { border: none; background: transparent; cursor: pointer; width: 20px; height: 26px;
+                 display: inline-flex; align-items: center; justify-content: center; color: #6b7280; padding: 0; }
+.pj-tree-caret .material-symbols-outlined { font-size: 18px; transition: transform .12s; }
+.pj-tree-caret.is-open .material-symbols-outlined { transform: rotate(90deg); }
+.pj-tree-caret-spacer { width: 20px; flex: 0 0 auto; }
+.pj-tree-link { display: flex; align-items: center; gap: 7px; flex: 1; min-width: 0;
+                text-decoration: none; color: inherit; padding: 5px 2px; }
+.pj-tree-icon { font-size: 18px; flex: 0 0 auto; }
+.pj-tree-name { font-size: 13.5px; overflow: hidden; text-overflow: ellipsis; white-space: nowrap; }
+.pj-tree-acts { display: none; gap: 0; flex: 0 0 auto; }
+.pj-tree-row:hover .pj-tree-acts { display: inline-flex; }
+.pj-tree-acts .pj-icon-btn { width: 22px; height: 22px; font-size: 14px; }
+
 /* 구글 머티리얼 심볼 아이콘(담당자) */
 .material-symbols-outlined { font-variation-settings: 'FILL' 0, 'wght' 400, 'GRAD' 0, 'opsz' 24; line-height: 1; vertical-align: middle; }
 .pj-gicon { font-size: 24px; color: #5f6368; flex: 0 0 auto; }
diff --git a/app/static/project.js b/app/static/project.js
index 1ad1c12..e7d376d 100644
--- a/app/static/project.js
+++ b/app/static/project.js
@@ -605,23 +605,85 @@
       } catch (e) { alert("삭제 실패: " + e.message); }
     });
 
-    // ── 서브프로젝트 추가/삭제 ──
-    const newSubBtn = el("pj-new-sub");
-    if (newSubBtn) newSubBtn.addEventListener("click", async function () {
-      const name = prompt("서브프로젝트 이름");
+    // ── 프로젝트 트리 (아사나식 접기/펼치기) ──
+    function setTreeOpen(li, open) {
+      const children = li.querySelector(":scope > .pj-tree-children");
+      const caret = li.querySelector(":scope > .pj-tree-row > .pj-tree-caret");
+      if (!children) return;
+      children.hidden = !open;
+      if (caret) { caret.setAttribute("aria-expanded", open ? "true" : "false"); caret.classList.toggle("is-open", open); }
+    }
+    function treeOpenSet() {
+      try { return new Set(JSON.parse(localStorage.getItem("pj_tree_open") || "[]")); }
+      catch (_) { return new Set(); }
+    }
+    function treeSaveOpen(id, open) {
+      const s = treeOpenSet();
+      if (open) s.add(String(id)); else s.delete(String(id));
+      try { localStorage.setItem("pj_tree_open", JSON.stringify(Array.from(s))); } catch (_) {}
+    }
+
+    document.querySelectorAll(".pj-tree-caret").forEach(function (caret) {
+      caret.addEventListener("click", function (e) {
+        e.preventDefault(); e.stopPropagation();
+        const li = caret.closest(".pj-tree-li");
+        const children = li.querySelector(":scope > .pj-tree-children");
+        const open = children.hidden;        // 현재 닫혀있으면 → 연다
+        setTreeOpen(li, open);
+        treeSaveOpen(li.dataset.id, open);
+      });
+    });
+
+    // 저장된 펼침 상태 복원 + 활성 프로젝트의 상위 자동 펼침
+    (function restoreTree() {
+      const openSet = treeOpenSet();
+      document.querySelectorAll(".pj-tree-li").forEach(function (li) {
+        if (openSet.has(String(li.dataset.id))) setTreeOpen(li, true);
+      });
+      const active = document.querySelector(".pj-tree-row.is-active");
+      let box = active ? active.closest(".pj-tree-children") : null;
+      while (box) {
+        box.hidden = false;
+        const li = box.closest(".pj-tree-li");
+        if (li) setTreeOpen(li, true);
+        box = li ? (li.parentElement ? li.parentElement.closest(".pj-tree-children") : null) : null;
+      }
+    })();
+
+    // 서브프로젝트 추가 (트리 각 노드)
+    document.querySelectorAll(".pj-tree-addsub").forEach(function (b) {
+      b.addEventListener("click", async function (e) {
+        e.preventDefault(); e.stopPropagation();
+        const name = prompt("서브프로젝트 이름");
+        if (!name || !name.trim()) return;
+        try {
+          await api("POST", "/project/api/projects/" + b.dataset.id + "/subprojects", { name: name.trim() });
+          location.reload();
+        } catch (err) { alert("생성 실패: " + err.message); }
+      });
+    });
+    // 프로젝트/서브 삭제 (트리)
+    document.querySelectorAll(".pj-tree-del").forEach(function (b) {
+      b.addEventListener("click", async function (e) {
+        e.preventDefault(); e.stopPropagation();
+        if (!confirm("'" + (b.dataset.name || "") + "' 삭제할까요? 하위 서브프로젝트·업무도 모두 삭제됩니다.")) return;
+        try {
+          await api("DELETE", "/project/api/projects/" + b.dataset.id);
+          if (String(b.dataset.id) === String(projectId)) location.href = "/project/";
+          else location.reload();
+        } catch (err) { alert("삭제 실패: " + err.message); }
+      });
+    });
+    // 새 최상위 프로젝트 (관리자)
+    const newProjSide = el("pj-new-project-side");
+    if (newProjSide) newProjSide.addEventListener("click", async function () {
+      const name = prompt("새 프로젝트 이름");
       if (!name || !name.trim()) return;
       try {
-        await api("POST", "/project/api/projects/" + projectId + "/subprojects", { name: name.trim() });
+        await api("POST", "/project/api/projects", { name: name.trim() });
         location.reload();
       } catch (e) { alert("생성 실패: " + e.message); }
     });
-    document.querySelectorAll(".pj-del-sub").forEach(function (b) {
-      b.addEventListener("click", async function () {
-        if (!confirm("이 서브프로젝트를 삭제할까요? (하위 업무도 모두 삭제)")) return;
-        try { await api("DELETE", "/project/api/projects/" + b.dataset.id); location.reload(); }
-        catch (e) { alert("삭제 실패: " + e.message); }
-      });
-    });
 
     // ── 멤버 배정/제외 (관리자) ──
     const memberModal = el("pj-modal-member");