diff --git a/src/idz/decoder/index.ts b/src/idz/decoder/index.ts
index 31d722e..afaabe1 100644
--- a/src/idz/decoder/index.ts
+++ b/src/idz/decoder/index.ts
@@ -36,6 +36,7 @@ import { saveTimeAttack1, saveTimeAttack2 } from "./saveTimeAttack";
 import { saveTopic } from "./saveTopic";
 import { unlockProfile } from "./unlockProfile";
 import { updateProvisionalStoreRank } from "./updateProvisionalStoreRank";
+import { updateTeamMember } from "./updateTeamMember";
 import {
   updateStoryClearNum1,
   updateStoryClearNum2,
@@ -100,6 +101,7 @@ const funcList: ReaderFn[] = [
   updateResult,
   updateStoryClearNum1,
   updateStoryClearNum2,
+  updateTeamMember,
   updateTeamPoints,
   updateUiReport,
   updateUserLog,
diff --git a/src/idz/decoder/updateTeamMember.ts b/src/idz/decoder/updateTeamMember.ts
new file mode 100644
index 0000000..04f9e23
--- /dev/null
+++ b/src/idz/decoder/updateTeamMember.ts
@@ -0,0 +1,17 @@
+import { RequestCode } from "./_defs";
+import { ExtId } from "../model/base";
+import { Team } from "../model/team";
+import { UpdateTeamMemberRequest } from "../request/updateTeamMember";
+import { AimeId } from "../../model";
+
+updateTeamMember.msgCode = 0x0073 as RequestCode;
+updateTeamMember.msgLen = 0x0010;
+
+export function updateTeamMember(buf: Buffer): UpdateTeamMemberRequest {
+  return {
+    type: "update_team_member_req",
+    action: buf.readUInt8(0x0004) === 0 ? "add" : "remove",
+    aimeId: buf.readUInt32LE(0x0008) as AimeId,
+    teamExtId: buf.readUInt32LE(0x000c) as ExtId<Team>,
+  };
+}
diff --git a/src/idz/encoder/index.ts b/src/idz/encoder/index.ts
index 0cfaa7f..6dbe659 100644
--- a/src/idz/encoder/index.ts
+++ b/src/idz/encoder/index.ts
@@ -29,6 +29,7 @@ import { saveTopic } from "./saveTopic";
 import { unlockProfile } from "./unlockProfile";
 import { updateProvisionalStoreRank } from "./updateProvisionalStoreRank";
 import { updateStoryClearNum } from "./updateStoryClearNum";
+import { updateTeamMember } from "./updateTeamMember";
 import { Response } from "../response";
 
 function encode(res: Response): Buffer {
@@ -120,6 +121,9 @@ function encode(res: Response): Buffer {
     case "update_story_clear_num_res":
       return updateStoryClearNum(res);
 
+    case "update_team_member_res":
+      return updateTeamMember(res);
+
     case "save_topic_res":
       return saveTopic(res);
 
diff --git a/src/idz/encoder/updateTeamMember.ts b/src/idz/encoder/updateTeamMember.ts
new file mode 100644
index 0000000..11dd1b3
--- /dev/null
+++ b/src/idz/encoder/updateTeamMember.ts
@@ -0,0 +1,10 @@
+import { UpdateTeamMemberResponse } from "../response/updateTeamMember";
+
+export function updateTeamMember(res: UpdateTeamMemberResponse): Buffer {
+  const buf = Buffer.alloc(0x0010);
+
+  buf.writeUInt16LE(0x0074, 0x0000);
+  buf.writeUInt32LE(res.status, 0x0004);
+
+  return buf;
+}
diff --git a/src/idz/handler/index.ts b/src/idz/handler/index.ts
index 82a00d9..130e49a 100644
--- a/src/idz/handler/index.ts
+++ b/src/idz/handler/index.ts
@@ -35,6 +35,7 @@ import { unlockProfile } from "./unlockProfile";
 import { updateProvisionalStoreRank } from "./updateProvisionalStoreRank";
 import { updateResult } from "./updateResult";
 import { updateStoryClearNum } from "./updateStoryClearNum";
+import { updateTeamMember } from "./updateTeamMember";
 import { updateTeamPoints } from "./updateTeamPoints";
 import { updateUiReport } from "./updateUiReport";
 import { updateUserLog } from "./updateUserLog";
@@ -158,6 +159,9 @@ export async function dispatch(
     case "update_story_clear_num_req":
       return updateStoryClearNum(w, req);
 
+    case "update_team_member_req":
+      return updateTeamMember(w, req);
+
     case "update_team_points_req":
       return updateTeamPoints(w, req);
 
diff --git a/src/idz/handler/updateTeamMember.ts b/src/idz/handler/updateTeamMember.ts
new file mode 100644
index 0000000..538f287
--- /dev/null
+++ b/src/idz/handler/updateTeamMember.ts
@@ -0,0 +1,37 @@
+import { _fixupPrevTeam } from "./_team";
+import { UpdateTeamMemberRequest } from "../request/updateTeamMember";
+import { UpdateTeamMemberResponse } from "../response/updateTeamMember";
+import { Repositories } from "../repo";
+
+export async function updateTeamMember(
+  w: Repositories,
+  req: UpdateTeamMemberRequest
+): Promise<UpdateTeamMemberResponse> {
+  const now = new Date();
+  const profileId = await w.profile().find(req.aimeId);
+  const teamId = await w.teams().find(req.teamExtId);
+
+  switch (req.action) {
+    case "add":
+      const prevTeamId = await w.teamMembers().findTeam(profileId);
+
+      await w.teamMembers().join(teamId, profileId, now);
+      await _fixupPrevTeam(w, prevTeamId);
+
+      break;
+
+    case "remove":
+      // TODO store expulsion flag in db
+      await w.teamMembers().leave(teamId, profileId);
+
+      break;
+
+    default:
+      throw new Error("???");
+  }
+
+  return {
+    type: "update_team_member_res",
+    status: 0,
+  };
+}
diff --git a/src/idz/request/index.ts b/src/idz/request/index.ts
index 8d319cd..8b5aef2 100644
--- a/src/idz/request/index.ts
+++ b/src/idz/request/index.ts
@@ -35,6 +35,7 @@ import { UnlockProfileRequest } from "./unlockProfile";
 import { UpdateProvisionalStoreRankRequest } from "./updateProvisionalStoreRank";
 import { UpdateResultRequest } from "./updateResult";
 import { UpdateStoryClearNumRequest } from "./updateStoryClearNum";
+import { UpdateTeamMemberRequest } from "./updateTeamMember";
 import { UpdateTeamPointsRequest } from "./updateTeamPoints";
 import { UpdateUiReportRequest } from "./updateUiReport";
 import { UpdateUserLogRequest } from "./updateUserLog";
@@ -77,6 +78,7 @@ export type Request =
   | UpdateProvisionalStoreRankRequest
   | UpdateResultRequest
   | UpdateStoryClearNumRequest
+  | UpdateTeamMemberRequest
   | UpdateTeamPointsRequest
   | UpdateUiReportRequest
   | UpdateUserLogRequest;
diff --git a/src/idz/request/updateTeamMember.ts b/src/idz/request/updateTeamMember.ts
new file mode 100644
index 0000000..6e71d42
--- /dev/null
+++ b/src/idz/request/updateTeamMember.ts
@@ -0,0 +1,10 @@
+import { ExtId } from "../model/base";
+import { Team } from "../model/team";
+import { AimeId } from "../../model";
+
+export interface UpdateTeamMemberRequest {
+  type: "update_team_member_req";
+  action: "add" | "remove";
+  aimeId: AimeId;
+  teamExtId: ExtId<Team>;
+}
diff --git a/src/idz/response/index.ts b/src/idz/response/index.ts
index ba65c36..edaad65 100644
--- a/src/idz/response/index.ts
+++ b/src/idz/response/index.ts
@@ -27,6 +27,7 @@ import { SaveTimeAttackResponse } from "./saveTimeAttack";
 import { SaveTopicResponse } from "./saveTopic";
 import { UpdateProvisionalStoreRankResponse } from "./updateProvisionalStoreRank";
 import { UpdateStoryClearNumResponse } from "./updateStoryClearNum";
+import { UpdateTeamMemberResponse } from "./updateTeamMember";
 import { UnlockProfileResponse } from "./unlockProfile";
 
 export type Response =
@@ -55,6 +56,7 @@ export type Response =
   | UnlockProfileResponse
   | UpdateProvisionalStoreRankResponse
   | UpdateStoryClearNumResponse
+  | UpdateTeamMemberResponse
   | SaveExpeditionResponse
   | SaveGarageResponse
   | SaveNewCarResponse
diff --git a/src/idz/response/updateTeamMember.ts b/src/idz/response/updateTeamMember.ts
new file mode 100644
index 0000000..babaa2e
--- /dev/null
+++ b/src/idz/response/updateTeamMember.ts
@@ -0,0 +1,4 @@
+export interface UpdateTeamMemberResponse {
+  type: "update_team_member_res";
+  status: number;
+}