A motor driving device includes a control unit which outputs a pre-driving signal to control a motor based on command information of an input target number of rotations and detection information of a number of rotations of the motor, and a motor driving unit which drives the motor based on the pre-driving signal. The control unit includes a speed control circuit which outputs speed command information based on the command information of the target number of rotations and the detection information, a stop control circuit which when an input of the command information of the target number of rotations is stopped, outputs stop command information after a predetermined time elapses from detection of stop of the motor, and a driving signal generation circuit which generates a control signal based on the stop command information and the speed command information.