The present invention provides a thermal energy recovery device that cools oil by means of a working medium and that can increase the energy input to the expander. The invention comprises an evaporator (10), an oil separator (12), an expander (14), a power recovery machine (16), a fuel supply flow path (18), a condenser (20), a pump (22), and a circulation flow path (24), an oil cooler (32), an oil cooling flow path (40), an expansion valve (V1) disposed at the upstream side of the oil cooler (32) of the oil cooling flow path (40), and an expansion valve adjusting part (62) adjusting the openness of the expansion valve. The oil cooler (32) enables at least a part of the mixed moving medium to evaporate through thermal exchange of oil flowing in the oil-supply flow path (18) and the mixed medium flowing in the oil cooling flow path (40). The end portion on the downstream side of the oil cooling flow path (40) is connected to the intermediate portion of the expander (14).