An embodiment of the present invention provides a vehicular open/close member control device provided with: a drive motor that is driven to close an open/close member fitted to a vehicle by rotating in a first direction or that is driven to open the open/close member by rotating in a second direction opposite to the first direction; a control unit that controls a rotation start operation of the drive motor and the rotation direction of the drive motor by outputting a control signal for switching connection of a switching unit; and a detection unit that outputs a signal indicating the rotation direction of the drive motor to the control unit. The control unit determines the presence or absence of seizure of the switching unit to a closing drive side on the basis of the signal from the detection unit, and, upon determining that there is seizure, performs at least one of the outputting of a control signal for activating a warning device for issuing a warning to a user and the shutting down of supply of power to the drive motor.