A door opening/closing device includes a detection unit which detects a foot of a person present near a front door; and a vehicle door opening/closing device main body which opens a rear slide door, when the detection unit detects the foot of the person, wherein when the foot of the person is not detected within a prescribed time after being detected, the detection unit outputs a pseudo outer door handle switch on signal which demands the vehicle door opening/closing device main body to open the rear slide door, and when detection is continuously performed during a prescribed time or longer from when the detection unit has detected a detection target, the detection unit does not output the pseudo outer door handle switch on signal.