An on-vehicle battery pack in which a battery module is housed with a gas release plane facing an inner surface of a sidewall portion of a pack case with a space therebetween, and a restriction plate includes a first plate portion protruding toward the sidewall portion at a height position higher than at least an upper edge of the gas release plane, and a second plate portion extending downwards in the space continuously from a front edge of the first plate portion in a direction in which the first plate portion protrudes.