A vapor power cycle apparatus that mixes part of high-temperature liquid-phase working fluid separated from a liquid-phase portion in a gas/liquid separator with high-temperature gas-phase working fluid extracted from a expander and allows the fluid to exchange heat with low-temperature liquid-phase working fluid from a condenser so as to efficiently recover the heat of working fluid and improve thermal efficiency of the entire cycle. The part of high-temperature liquid-phase working fluid separated from the liquid-phase portion in the gas/liquid separator is extracted, the resultant fluid is mixed in a second absorber with high-temperature gas-phase working fluid extracted from an interstage point in the expander to allow liquid-phase working fluid to absorb part of gas-phase working fluid and the high-temperature working fluid is used to heat low-temperature liquid-phase working fluid in a first heater without passing an extracted portion of high-temperature liquid-phase working fluid through a condenser.