An opening/closing body drive device includes: a motor which opens or closes an opening/closing body; a drive unit which rotates the motor; and a control unit which controls the drive unit. The drive unit includes a first and second integrated circuits having first and second switching elements and third and fourth switching elements which are connected to each other in series with respect to a power source and connection points of which are connected to one and the other terminals of the motor, respectively. The control unit turn-on drives the first and fourth switching elements or the second and third switching elements when driving the motor to be rotated forward or reversely. The control unit turn-on drives any one of the second and third switching elements when braking the motor during the forward rotation of the motor.