A binary power generation system comprising a plurality of displacement type expanders (6A-6C) and a plurality of power generators (7A-7C) connected to each of the displacement type expanders (6A-6C), and generating power by expansion of an operating medium, which has received heat from a heat source medium for vaporization, at least at one of the displacement type expanders (6A-6C), the system comprising: a plurality of evaporators (4A-4C) that is connected to each of the corresponding displacement type expanders (6A-6C) and vaporizes the operating medium using the heat from the heat source medium; a condenser that is connected to each of the displacement type expanders (6A-6C), and cools and condenses the operating medium expanded at least at one of the displacement type expanders (6A-6C); characterized in that the system further comprises: a plurality of branched lines (L1A-L1C) branched from a line through which the heat source medium circulates, each of the branched lines (L1A-L1C) passing through each of the plurality of evaporators (4A-4C); a stop means (14A - 14C, 16A - 16C) capable of stopping circulation of the operating medium for each set of the evaporators (4A-4C) and the displacement type expanders (6A-6C) and circulation of the heat source medium for each of the evaporators (4A, 4B, or 4C) through the branched lines (L1A-L1C); and a control unit that controls the numbers of the evaporators (4A-4C) and the displacement type expanders (6A-6C) to be operated by controlling the stop means (16A-16C) based on information on a heat amount of the heat source medium. a plurality of evaporators (4A-4C) that is connected to each of the corresponding displacement type expanders (6A-6C) and vaporizes the operating medium using the heat from the heat source medium; a condenser that is connected to each of the displacement type expanders (6A-6C), and cools and condenses the operating medium expanded at least at one of the displacement type expanders (6A-6C); characterized in that the system further comprises: a plurality of branched lines (L1A-L1C) branched from a line through which the heat source medium circulates, each of the branched lines (L1A-L1C) passing through each of the plurality of evaporators (4A-4C); a stop means (14A - 14C, 16A - 16C) capable of stopping circulation of the operating medium for each set of the evaporators (4A-4C) and the displacement type expanders (6A-6C) and circulation of the heat source medium for each of the evaporators (4A, 4B, or 4C) through the branched lines (L1A-L1C); and a control unit that controls the numbers of the evaporators (4A-4C) and the displacement type expanders (6A-6C) to be operated by controlling the stop means (16A-16C) based on information on a heat amount of the heat source medium. a plurality of branched lines (L1A-L1C) branched from a line through which the heat source medium circulates, each of the branched lines (L1A-L1C) passing through each of the plurality of evaporators (4A-4C); a stop means (14A - 14C, 16A - 16C) capable of stopping circulation of the operating medium for each set of the evaporators (4A-4C) and the displacement type expanders (6A-6C) and circulation of the heat source medium for each of the evaporators (4A, 4B, or 4C) through the branched lines (L1A-L1C); and a control unit that controls the numbers of the evaporators (4A-4C) and the displacement type expanders (6A-6C) to be operated by controlling the stop means (16A-16C) based on information on a heat amount of the heat source medium.