An electronic control unit for an engine-driven heat pump, the engine-driven heat pump comprising: an outdoor exchanger suitable to perform a heat exchange with an outside air, a waste heat collector connected in parallel with the-outdoor heat exchanger in the case that the outdoor heat exchanger functions as an evaporator and-is suitable to perform a heat exchange with engine waste heat, a supercooler is connected in parallel with the outdoor heat exchanger and the waste heat collector in the case suitable to perform a heat exchange with a liquid coolant, a first expansion valve is provided at an inlet of the outdoor heat exchanger in the case so as to employ a superheat degree of an outlet of the outdoor heat exchanger as a control target, a second expansion valve is provided at an inlet of the waste heat collector in the case so as to employ a superheat degree of an outlet of the waste heat collector as a control target, and a third expansion valve is provided at an inlet of the supercooler in the case so as to employ a superheat degree of an outlet of the supercooler as a control target, wherein a superheat degree in a compressor suction route at the downstream of a confluence of the outdoor heat exchanger outlet route, the waste heat collector outlet route and the supercooler outlet route in the case is employed as a suction superheat degree, characterized in that: the suction superheat degree is suitable to be selected as the control target instead of the superheat degree at the outlet of each of the outdoor heat exchanger, the waste heat collector and the supercooler, and the electronic control unit is configured to select the suction superheat degree as the control target of the first expansion valve and to employ the superheat degree at the outlet of each of the waste heat collector and the supercooler as the control target of the corresponding valves (32, 33) such that the optimal main evaporator is selected according to outside air temperature or heating load. an outdoor exchanger suitable to perform a heat exchange with an outside air, a waste heat collector connected in parallel with the-outdoor heat exchanger in the case that the outdoor heat exchanger functions as an evaporator and-is suitable to perform a heat exchange with engine waste heat, a supercooler is connected in parallel with the outdoor heat exchanger and the waste heat collector in the case suitable to perform a heat exchange with a liquid coolant, a first expansion valve is provided at an inlet of the outdoor heat exchanger in the case so as to employ a superheat degree of an outlet of the outdoor heat exchanger as a control target, a second expansion valve is provided at an inlet of the waste heat collector in the case so as to employ a superheat degree of an outlet of the waste heat collector as a control target, and a third expansion valve is provided at an inlet of the supercooler in the case so as to employ a superheat degree of an outlet of the supercooler as a control target, wherein a superheat degree in a compressor suction route at the downstream of a confluence of the outdoor heat exchanger outlet route, the waste heat collector outlet route and the supercooler outlet route in the case is employed as a suction superheat degree, characterized in that: the suction superheat degree is suitable to be selected as the control target instead of the superheat degree at the outlet of each of the outdoor heat exchanger, the waste heat collector and the supercooler, and the electronic control unit is configured to select the suction superheat degree as the control target of the first expansion valve and to employ the superheat degree at the outlet of each of the waste heat collector and the supercooler as the control target of the corresponding valves (32, 33) such that the optimal main evaporator is selected according to outside air temperature or heating load.