An electronic control unit (ECU) of an engine system starts a control (preheat) that supplies heat reserving hot water stored in a heat accumulating device to an engine prior to an engine start. The ECU determines a time that continues the preheat on the basis of a cooling water temperature of the engine so as to execute the engine start after a warming-up of the engine is reliably finished. Further, during the execution of the preheat, a lighting lamp is turned on, and that incidence is recognized to a driver. When the preheat is completed, the ECU automatically starts the engine.