The purpose of the present invention is to provide: a means for simply rendering control of the temperature of a warming material possible at lower cost, the means being usable instead of or in combination with the conventional temperature control performed by controlling the supply amount of oxygen or air with an air-permeable film or the like； and a warming material including the temperature control means. The invention further provides: an advanced temperature control means which is utilizable for warming materials for medical use； and an improved warming material for medical applications which is safer and more effective. The temperature control agent according to an embodiment of the invention is for controlling the heating temperature of a warming material including a heating composition which generates heat upon reaction with oxygen, and is characterized by comprising one or more aliphatic compounds which have a melting point of 35-65°C and have a solubility in water (g/100 mL) at 20°C of 5 or less.
