A motor controller, operatively connected to a motor having an output shaft, includes a rotary detector to detect a rotation direction and a rotation amount of the output shaft of the motor to generate an actual rotary signal, a drive controller to generate a control signal based on the actual rotary signal and a target rotary signal indicating a target rotary direction and a target rotary amount, and a driver to supply a driving power to the motor based on the control signal. When the motor is in a hold state, the control signal is reversed periodically for a predetermined reverse time period T2 per a predetermined one reverse cycle T1. When the control signal is not reversed for a certain lock detection time period Tr that is longer than the revere cycle T1 of the control signal, supply of the driving power to the motor is blocked.