The present invention provides a regenerative heat pump system including a heat pump cycle, first storage vessel for storing a heat storage material, heat exchange device between first refrigerant and heat storage material for heating and decomposing the heat storage material by heat from a refrigerant, and heat exchange device between second refrigerant and an other heat storage material for transferring heat from the separated heat storage material to the refrigerant. The system also includes second storage vessel for storing the decomposed heat storage material, and heat generating device for generating heat by recombining the heat storage material stored in the second storage vessel and for heating a heating medium. The heat exchange device between the first refrigerant and the heat storage material is also used as a radiator of the heat pump cycle, and the heat exchange device between second refrigerant and the other heat storage material is also used as at least a part of an evaporator of the heat pump cycle.