By employing a heat source control section that controls the operating state of an internal combustion engine mounted in a vehicle, a necessary heat calculating section that calculates the engine coolant temperature needed by a heater core, which consumes the heat supplied from the engine through engine coolant water, and the time at which this engine coolant temperature becomes necessary, a heat supply estimating section that estimates engine coolant temperature at the aforementioned time in a case in which the engine is operated continuously in the current operating state, and a heat generation increase requesting section that requests the heat source control section to increase heat generation quantity of the engine when the engine coolant temperature estimated by the heat supply estimating section is less than the engine coolant temperature calculated by the necessary heat calculating section, the heat necessary for the heater core is supplied more efficiently and adequately.