To provide a motor device that reduces load on a switching element, and also reduces power consumption, and to provide a pump with the motor device.

The motor device 1 includes, a rotor 2, a stator 3 that drives the rotor 2, the switching element 4 that is externally supplied with power and energizes the stator 3, and a control unit 5 that outputs a control signal 11 for controlling the switching element 4 according to an external command signal 10. Supply voltage externally supplied to the control unit 5 and the regulator voltage 14 of the control unit 5 are lower than the voltage of power supplied to the switching element 4. The pump 20 uses the motor device 1 as a driving source. The motor device further includes a voltage detection unit 6 that detects at least either of the regulator voltage 14 of the control unit 5 and the supply voltage and a signal transfer permitting device 7 that permits transfer of the control signal 11 when voltage is detected by the voltage detection unit 6.