diff --git a/src/lib/api.ts b/src/lib/api.ts
index b2bcfc9..29a35cd 100644
--- a/src/lib/api.ts
+++ b/src/lib/api.ts
@@ -2,7 +2,7 @@ import axios from "axios";
 import type {
   Account, AcctSummary, ApprovalQueue, Attendance, AuditLog, ClientContact,
   Company, Contract, ContractFile, Dashboard, Department, DirectoryEntry, IncentiveConfig,
-  LeaveBalance, LeaveRequest, MailNote, Me, Member, MyIncentive, NavItem, Notification,
+  LeaveBalance, LeaveRequest, MailFull, MailNote, Me, Member, MyIncentive, NavItem, Notification,
   OvertimeRequest, PaymentSplit, PaymentStage, Product, Project, ProjectMailsResponse,
   ProjectMember, ProjectTask, Settlement, SimResult, TaskComment, TaxRecord, Timesheet, Transaction,
   UserIncentive, Version, WorkPolicy, WorkStatusEvent, WorkStatusKind,
@@ -153,6 +153,12 @@ export const getMailNotes = (id: string) =>
   api.get<MailNote[]>(`/projects/${id}/mail-notes`).then((r) => r.data);
 export const putMailNote = (id: string, messageId: string, body: string) =>
   api.put<MailNote>(`/projects/${id}/mail-notes`, { messageId, body }).then((r) => r.data);
+export const getMailFull = (id: string, messageId: string) =>
+  api.get<MailFull>(`/projects/${id}/mails/full`, { params: { messageId } }).then((r) => r.data);
+export const mailAttachmentUrl = (
+  id: string,
+  p: { messageId: string; gmailMsgId: string; attachmentId: string; filename: string }
+) => `/api/projects/${id}/mails/attachment?${new URLSearchParams(p).toString()}`;
 export const syncProjectMails = (id: string) =>
   api.post(`/projects/${id}/mails/sync`).then((r) => r.data);
 export const hideMail = (id: string, messageId: string, hidden: boolean) =>
diff --git a/src/pages/ProjectDetail.tsx b/src/pages/ProjectDetail.tsx
index 985cba7..17b9bdf 100644
--- a/src/pages/ProjectDetail.tsx
+++ b/src/pages/ProjectDetail.tsx
@@ -9,7 +9,7 @@ import {
   getProject, getProjectMembers, getContacts, getTasks, getContract, getContractFiles,
   getPayments, upsertProjectMember, deleteProjectMember, createTask, updateTask, deleteTask,
   getTaskComments, createTaskComment, deleteTaskComment,
-  getProjectMails, putMailNote, syncProjectMails, hideMail,
+  getProjectMails, putMailNote, syncProjectMails, hideMail, getMailFull, mailAttachmentUrl,
   upsertContact, deleteContact, patchProjectNotes, putContract, uploadContractFile, getFileDownloadUrl,
   deleteContractFile, createPayment, updatePayment, deletePayment, recomputeProject,
   updateProject,
@@ -596,6 +596,13 @@ function MailRow({ projectId, mail, nameOf }: { projectId: string; mail: Project
   const hide = useMutation({ mutationFn: () => hideMail(projectId, mail.messageId, !mail.hidden), onSuccess: invalidate });
   const when = mail.ts ? formatDateTime(new Date(mail.ts).toISOString()) : mail.date;
   const rcpt = recipientSummary(mail.to, mail.cc);
+  // 펼칠 때만 본문 전문 + 첨부 리스트를 온디맨드로 가져온다.
+  const fullQ = useQuery({
+    queryKey: ["mail-full", projectId, mail.messageId],
+    queryFn: () => getMailFull(projectId, mail.messageId),
+    enabled: open,
+    staleTime: 5 * 60_000,
+  });
 
   return (
     <Card className={classNames("overflow-hidden", mail.hidden && "opacity-60")}>
@@ -640,7 +647,7 @@ function MailRow({ projectId, mail, nameOf }: { projectId: string; mail: Project
         </div>
       </div>
       {open && (
-        <div className="px-4 pb-4 pt-2 border-t border-divider">
+        <div className="px-4 pb-4 pt-2 border-t border-divider space-y-3">
           <div className="text-xs text-ink-muted grid grid-cols-1 sm:grid-cols-2 gap-x-6 gap-y-1">
             <div className="sm:col-span-2"><span className="text-ink-secondary font-medium">보낸사람</span> {mail.from}</div>
             <div className="sm:col-span-2"><span className="text-ink-secondary font-medium">받는사람</span> {mail.to || "—"}</div>
@@ -648,6 +655,42 @@ function MailRow({ projectId, mail, nameOf }: { projectId: string; mail: Project
             <div><span className="text-ink-secondary font-medium">시각</span> {when}</div>
             <div><span className="text-ink-secondary font-medium">발견 메일함</span> {nameOf(mail.mailbox)}</div>
           </div>
+
+          {/* 메일 전문 (본문) */}
+          <div>
+            <div className="flex items-center justify-between mb-1">
+              <span className="form-label !mb-0">메일 전문</span>
+              <a href={gmailUrl(mail.messageId)} target="_blank" rel="noopener noreferrer" className="text-[11px] text-navy hover:underline inline-flex items-center gap-1">Gmail에서 열기 <ExternalLink size={11} /></a>
+            </div>
+            {fullQ.isLoading ? (
+              <div className="text-sm text-ink-muted py-4">본문 불러오는 중…</div>
+            ) : fullQ.isError ? (
+              <div className="text-sm text-status-pending-fg py-4">본문을 불러오지 못했습니다. (메일 연동/권한 확인)</div>
+            ) : fullQ.data?.isHtml ? (
+              <iframe title="메일 본문" sandbox="" srcDoc={fullQ.data.body}
+                className="w-full h-80 border border-divider rounded-control bg-white" />
+            ) : (
+              <pre className="whitespace-pre-wrap break-words text-sm text-ink-secondary bg-canvas/50 border border-divider rounded-control p-3 max-h-80 overflow-auto font-sans">{fullQ.data?.body || "(본문 없음)"}</pre>
+            )}
+          </div>
+
+          {/* 첨부파일 리스트 */}
+          {(fullQ.data?.attachments?.length ?? 0) > 0 && (
+            <div>
+              <span className="form-label">첨부파일 ({fullQ.data!.attachments.length})</span>
+              <div className="flex flex-wrap gap-2">
+                {fullQ.data!.attachments.map((a) => (
+                  <a key={a.attachmentId}
+                    href={mailAttachmentUrl(projectId, { messageId: mail.messageId, gmailMsgId: fullQ.data!.gmailId, attachmentId: a.attachmentId, filename: a.filename })}
+                    className="inline-flex items-center gap-2 text-sm text-ink border border-border rounded-control px-3 py-1.5 hover:border-navy hover:bg-navy-subtle/30">
+                    <Download size={14} className="text-navy" />
+                    <span className="truncate max-w-[200px]">{a.filename}</span>
+                    <span className="text-[11px] text-ink-muted">{formatSize(a.size)}</span>
+                  </a>
+                ))}
+              </div>
+            </div>
+          )}
         </div>
       )}
     </Card>
diff --git a/src/types.ts b/src/types.ts
index 09aafee..25a5c4b 100644
--- a/src/types.ts
+++ b/src/types.ts
@@ -231,6 +231,20 @@ export interface MailNote {
   updatedAt: string;
 }
 
+export interface MailAttachment {
+  filename: string;
+  mimeType: string;
+  size: number;
+  attachmentId: string;
+}
+
+export interface MailFull {
+  gmailId: string;
+  body: string;
+  isHtml: boolean;
+  attachments: MailAttachment[];
+}
+
 export interface ProjectMember {
   id: string;
   projectId: string;