A cluster system of mutual standby type forms groups each composed of a job execution system and a job standby system for taking over the job when problems occur in the job execution system, and provides information processing devices each with a job execution system and a job standby system of different groups. The information processing devices each include: an upper limit value storage unit for storing a power upper limit value, a power control unit for controlling use of power by its own information processing device so as not to exceed the power upper limit value stored, and an upper limit value setting unit for causing the upper limit value storage unit to store a power upper limit value smaller than the maximum power consumption of its own information processing device when it is not necessary to take over the job of another information processing device.