diff --git a/luprex/core/cpp/world.cpp b/luprex/core/cpp/world.cpp
index e8f95541..d3cc182a 100644
--- a/luprex/core/cpp/world.cpp
+++ b/luprex/core/cpp/world.cpp
@@ -471,6 +471,9 @@ LuaDefine(tangible_animate, "c") {
     int64_t id = w->id_global_pool_.alloc_id_for_thread(L);
     AnimStep step;
     step.from_lua(L, config.index());
+    if (step.action() == "") {
+        luaL_error(L, "animation action must be specified");
+    }
     tan->anim_queue_.add(id, step);
     tan->update_plane_item();
     return LS.result();