A motor unit includes a motor; a driving circuit that supplies a driving current to the motor; a shunt resistor; a rotation command input terminal; a pulse output terminal; a current detection unit detects a driving current measured by the shunt resistor; a driving control unit that controls supplying of the driving current; a storage unit that previously stores allowable range information; a current value determination unit that determines whether or not the current value of the driving current is included in the allowable range, and the allowable range information stored in the storage unit; and a signal generation unit that generates the pulse signal by setting a duty ratio of the pulse signal as a first duty ratio, and setting the duty ratio of the pulse signal as a second duty ratio different from the first duty ratio.