To provide a geothermal heat utilization heat pump type water heater suppressing lowering of a ground temperature, and operating a heat pump with high efficiency.

A hot water storage control section 14 drives a geothermal heat circulation pump 22 before a late-night time zone, and when a temperature detected by a ground going temperature detecting means 23 or a ground returning temperature detecting means 24 is lower than a prescribed temperature, a boiling-up operation is performed with a heating capacity of a heat pump type heating means 2 lower than a rated heating capacity. Thus the heating capacity of the heat pump type heating means is reduced in comparison with the rated heating capacity usually used, heat collection output pumped up from the ground is reduced, and the difference from a temperature recovering capacity of the ground is reduced, as a result, the lowering of the ground temperature can be suppressed, and the heat pump type heating means 2 can be operated with high efficiency.