Engine waste heat recovering apparatus

An engine cooling unit (6A) and an exhaust gas heat exchanger (9) for use with the exhaust gas from an engine (2) are connected with a circulation path (12) for circulating a heat transfer medium. The output of the circulation path (12) is connected via a conduit (18) to an output heat exchanger (20) installed in e.g. a hot water storage tank (17). The exhaust gas heat exchanger (9) is disposed across the circulation path (12) at the upstream side of the engine cooling unit (6A) of the engine (2). The heat transfer medium introduced into the exhaust gas heat exchanger (9) is set to a lower temperature enough to maintain the temperature of vapor in the exhaust gas of which heat is transferred to the heat transfer medium lower than the dew point. The heat transfer medium after drawing generic heat from the exhaust gas and receiving its condensation heat in the exhaust gas heat exchanger (9) is passed to the engine cooling unit (6A) where it draws more heat. Accordingly, the heat generated by the engine (2) can be recovered at a higher efficiency.