A vehicular electric power source control device provided on a vehicle provided with an engine that may be stopped even in a vehicle drivable state which is established when a predetermined condition is satisfied and in which a vehicle drive force can be generated, and an electric-energy storage device which is charged by an operation of said engine, the vehicular electric power source control device permitting implementation of an automatic engine starting control to start said engine when an amount of an electric energy stored in said electric-energy storage device has been reduced to or below a predetermined charging start threshold value while the engine is held at rest in said vehicle drivable state, the vehicle electric power source control device includes an engine start permitting portion configured to permit the implementation of said automatic engine starting control under a condition that any passenger is present within the vehicle.