To provide an engine driven type heat pump apparatus which can prevent the freezing of drain water by efficiently raising the temperature thereof while restricting power consumption without enlarging the structure thereof.

This engine driven type heat pump apparatus is provided with a compressor of a refrigerant circulating through a heat pump circuit, an engine for driving the compressor, an exhaust heat exchanger provided on an exhaust path of the engine, a neutralizer 52 communicating with the exhaust heat exchanger through a drain path (a), and a drain discharge pipe 57 to discharge drain water from the neutralizer 52. A heater 72 is provided inside the neutralizer 52, a metal bar 73 is inserted through the drain discharge pipe 57 and the heater 72 is thermally connected to the metal bar 73.