Production of condensed water in an intercooler is suppressed. The apparatus comprises a high temperature system cooling water passage through which cooling water having a high temperature flows; a low temperature system cooling water passage which is a cooling water passage through which cooling water having a low temperature flows and which passes through at least the intercooler; two communication passages which communicate the high temperature system cooling water passage and the low temperature system cooling water passage, one of the communication passages through which the cooling water flows from the high temperature system cooling water passage toward the low temperature system cooling water passage, and the other through which the cooling water flows from the low temperature system cooling water passage toward the high temperature system cooling water passage; valves which are provided for the communication passages respectively; and a control unit which controls the valves provided for the communication passages respectively so that a temperature of the gas flowing out from the intercooler is higher than a dew point temperature.