To provide a getting on and off assisting device capable of forming a gentle slope even in the case there is a large difference in level between the floor surface of an entrance and a landing surface at the external part of a vehicle.

The getting on and off assisting device for a vehicle comprises a storage space 4 in a mode corresponding to that of a floor plate 2 of a vehicle; a flat plate member 6 capable of being stored in a horizontal state in its space; a guide 5 extending in the storage space in the getting on and off direction; a push pull chain 7 extending from one end part, coupled to the flat plate member to the other end side along the guide; a sprocket 9 extending around the other end side of the push pull chain; a motor, not shown, coupled to a drive shaft 8 of the sprocket; a roller 10 rotatably supporting the rear end part of the flat plate member by the guide; and a reduction gear, not shown, located between the motor and the sprocket.