To provide an automatic operation device for a motor pump making an opening/closing mechanism itself compact by making contact capacity small by reducing current flowing to the opening/closing mechanism built in an electric circuit for operation control in the motor pump using a three-phase induction motor as a prime mover, and making the motor pump light weigh and compact by reducing a storage space by using one kind of opening/closing mechanism shared for both automatic operation control of the motor pump and burning protection of the motor.

A temperature detector 4 for detecting abnormal heat generation of the three-phase induction motor 7 and a water level detector 3 detecting liquid level, a control device 5 for controlling operation of the motor pump based on the detection signal, and the opening/closing mechanism 6 for connecting and disconnecting a part in delta connection of motor winding 2, are built in the electric circuit for operation control of the motor pump. The opening/closing mechanism 6 is shared for both functions for burning protection of the motor 7 and automatic operation control of the motor pump.