diff --git a/mock/src/ui/phy/PhyToolbar.vue b/mock/src/ui/phy/PhyToolbar.vue
index f4eebbc..8ba24e6 100644
--- a/mock/src/ui/phy/PhyToolbar.vue
+++ b/mock/src/ui/phy/PhyToolbar.vue
@@ -69,6 +69,7 @@ function addPart(e: Event) {
       ◇
     </button>
     <select
+      class="move-to"
       aria-label="移し先…"
       :disabled="mismatch || !selectedCount"
       @change="emit('moveTo', ($event.target as HTMLSelectElement).value)"
@@ -113,4 +114,8 @@ function addPart(e: Event) {
 .tools select {
   font-size: 12px;
 }
+/* 候補の名前でセレクトの幅が変わると、ツールバーが折り返してキャンバスの大きさが変わる */
+.tools select.move-to {
+  width: 6em;
+}
 </style>