To provide a cold storage device for cold reserving compartment the heat-exchanging ability of which can be prevented surely from being deteriorated by the sticking of a heat carrier increased in viscosity due to a temperature drop.

This heat storage device is constituted in such a way that, when the flow rate of the heat carrier in a heat carrier circulating circuit 21 becomes a prescribed value or lower, the compressor 24a of a refrigerating circuit 24 is stopped. Therefore, even when the heat carrier which is increased in viscosity due a temperature drop sticks to the evaporating pipe 24d of a heat exchanger 23, the sticking heat carrier can be removed quickly by stopping the compressor 24a.