A control device for a vehicular opening/closing body is provided with a duty ratio calculator (78), which calculates a duty ratio when power supplied to a door drive motor (48) allowing an opening/closing body to open/close is subjected to duty control based on a result of adding first second multiplication values, the first multiplication value being obtained by multiplying a speed difference between a target opening/closing body speed and an actual opening/closing body speed by a negative proportional gain, and the second multiplication value being obtained by multiplying an integral value of the speed difference by an integral gain.