An object of the present invention is to provide a solar heat steam cycle system capable of operating efficiently and stably in keeping with the status of collected or stored heat, and a control method for use with the system.The system includes a heat collector (1) which collects solar thermal energy, a thermal storage device (2) which stores the solar thermal energy collected by the heat collector, a feed water heater (3) which heats feed water, an evaporator (4) which evaporates the feed water supplied from the feed water heater, and a steam turbine (6) driven by steam generated by the evaporator. The system includes a control valve (31) which controls allocations of heating medium supplied from the thermal storage device to the evaporator and the feed water heater.