An emergency stop circuit of a teaching operation panel by which the teaching operation panel can be connected to and disconnected from a robot control device under predetermined conditions and the operation of a robot is not stopped even if the teaching operation panel is disconnected from the robot control device. When the robot, which has already been taught and is automatically operated, comes into contact with a connection cable between the teaching operation panel and the robot control device and disconnects the teaching operation panel from the robot control device, the emergency stop function of the robot is effected. When, however, the teaching operation panel is disconnected from a port while a connecting/disconnecting switch is turned ON, the emergency stop function of the robot is not effected. With this arrangement, the teaching operation panel can be disconnected from the robot control device while the robot is automatically operated.