The present disclosure provides a plug interlock device for a circuit breaker, comprising: a lever-type withdrawable interlock assembly provided at a transfer car so that inputting and withdrawal of a breaker main body can be locked; a plug connector assembly, which rises/lowers in response to insertion or separation of a control line plug into or from a connector provided at the upper part of the breaker main body; a shaft, which rotates in different directions according to the elevation of the plug connector assembly by connecting one side thereof to the lower end of the plug connector assembly; and a blocking plate connected to the other side of the shaft so as to lock or unlock the operation of the lever-type withdrawable interlock assembly while horizontally moving according to the rotation of the shaft.