AMP (2-Amino-2-Methyl-1, 3-Propanediol) does not release the absorbed heat during temperature drop but releases it during temperature rise. Also, AMP keeps a solid state upon the heat release. The heat storage material which is the aggregate of AMP is arranged to exchange heat with the subject for warm-up. In the warm-up acceleration control, it is judged whether or not there is a request for warm-up to the subject for warm-up (step S10). If it is judged that there is the request for warm-up, it is judged whether or not the radiation condition of the heat storage material is satisfied (step S12). If it is judged that the radiation condition is satisfied, the heater is started to operate (step S14). By operating the heater, the heat storage material is directly or indirectly heated.