A multi-pressure radial turbine system including a high-pressure pump and a low-pressure pump for pressurizing liquid-phase heating media introduced therein to different pressures; a high-pressure evaporator and a low-pressure evaporator for vaporizing the liquid-phase heating media delivered from the high-pressure pump and the low-pressure pump by absorbing heat from a high-temperature heat source; one multi-pressure radial turbine that expands the gaseous heating media having different pressures and temperatures, supplied from the high-pressure evaporator and the low-pressure evaporator, to obtain output power; and a condenser for condensing the gaseous heating medium expanded in the multi-pressure radial turbine by making the medium release heat to a low-pressure heat source. A cycle circuit is formed through which the heating medium circulates while repeatedly changing its state between vapor and liquid.