A solar thermal power generation system comprising: a solar heat collection system that uses water/steam as a heat medium, the solar heat collection system being configured to generate superheated steam from water by collecting solar heat; and a main power generation system that uses the heat medium in common with the solar heat collection system, the main power generation system being configured to perform power generation by using part of the superheated steam generated by the solar heat collection system, the main power generation system including a steam turbine (21, 22, 23) into which part of the superheated steam generated by the solar heat collection system is introduced and a main generator driven by the steam turbine; and a solar heat storage/release system that uses a heat storage medium different from the heat medium of the solar heat collection system, the solar heat storage/release system being configured to store heat in the heat storage medium by heat exchange with the rest of the superheated steam generated by the solar heat collection system and to release the heat stored in the heat storage medium; and a secondary power generation system that uses the heat medium in common with the solar heat collection system, the secondary power generation system being configured to perform power generation by using saturated steam generated from the heat medium by heat storage or heat release of the heat storage medium in the solar heat storage/release system, characterised in that the solar heat storage/release system includes: a heat storage heater for exchanging heat between the rest of the superheated steam generated by the solar heat collection system and the heat storage medium to store heat in the heat storage medium and to generate saturated steam from the superheated steam; a low-temperature tank for containing the heat storage medium to be supplied to the heat storage heater; and a high-temperature tank for containing the heat storage medium after storing heat in the heat storage heater, and the secondary power generation system includes: a saturated steam turbine into which the saturated steam generated by the heat storage heater can be introduced; and a secondary generator driven by the saturated steam turbine. a solar heat collection system that uses water/steam as a heat medium, the solar heat collection system being configured to generate superheated steam from water by collecting solar heat; and a main power generation system that uses the heat medium in common with the solar heat collection system, the main power generation system being configured to perform power generation by using part of the superheated steam generated by the solar heat collection system, the main power generation system including a steam turbine (21, 22, 23) into which part of the superheated steam generated by the solar heat collection system is introduced and a main generator driven by the steam turbine; and a solar heat storage/release system that uses a heat storage medium different from the heat medium of the solar heat collection system, the solar heat storage/release system being configured to store heat in the heat storage medium by heat exchange with the rest of the superheated steam generated by the solar heat collection system and to release the heat stored in the heat storage medium; and a secondary power generation system that uses the heat medium in common with the solar heat collection system, the secondary power generation system being configured to perform power generation by using saturated steam generated from the heat medium by heat storage or heat release of the heat storage medium in the solar heat storage/release system, characterised in that the solar heat storage/release system includes: a heat storage heater for exchanging heat between the rest of the superheated steam generated by the solar heat collection system and the heat storage medium to store heat in the heat storage medium and to generate saturated steam from the superheated steam; a low-temperature tank for containing the heat storage medium to be supplied to the heat storage heater; and a high-temperature tank for containing the heat storage medium after storing heat in the heat storage heater, and a heat storage heater for exchanging heat between the rest of the superheated steam generated by the solar heat collection system and the heat storage medium to store heat in the heat storage medium and to generate saturated steam from the superheated steam; a low-temperature tank for containing the heat storage medium to be supplied to the heat storage heater; and a high-temperature tank for containing the heat storage medium after storing heat in the heat storage heater, and the secondary power generation system includes: a saturated steam turbine into which the saturated steam generated by the heat storage heater can be introduced; and a secondary generator driven by the saturated steam turbine. a saturated steam turbine into which the saturated steam generated by the heat storage heater can be introduced; and a secondary generator driven by the saturated steam turbine.