A compressor, a first heat exchanger, a first heat storage unit, a pressure accumulation unit, a second heat exchanger, and a second heat storage unit are provided. The first heat storage unit and the second heat storage unit are connected by a first flow passage and a second flow passage. The first and second flow passages are connected by a third flow passage. A first on-off means is provided in a first region of the first flow passage and a second on-off means is provided in a second region. A third on-off means is provided in a third region of the second flow passage, and a fourth on-off means is provided in a fourth region. A driving means and a heating means are provided in the third flow passage.