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 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 only the second switching element when braking the motor during the forward rotation and turn-on drives only the fourth switching element when braking the motor during the reverse rotation, or turn-on drives only the third switching element when braking the motor during the forward rotation and turn-on drives only the first switching element when braking the motor during the reverse rotation.