Abstract: In an apparatus for permitting pass-through between a vehicle compartment and a trunk room of a motor vehicle, a first hook is provided on a forward foldable portion of a seat back of the rear seat, and a second hook that is engageable with the first hook is provided on the seat back. The first and second hooks are normally biased by coil springs in such a direction as to engage these hooks with each other. A vehicle-compartment-side strap and a trunk-room-side strap are provided for rotating the first hook and the second hook, respectively, so as to release the engagement of these hooks. A lock device is also provided for limiting rotation of the first hook while the forward foldable portion is in the upright portion, thus making it impossible to release the engagement of the first hook with the second hook by pulling the vehicle-compartment-side strap.