To remarkably delay the increase of the temperature of the interior of an utensil protecting containing device, such as a placing bed and a safe, and to protect an utensil from a high temperature until a fire ends.

This increase temperature decreasing device 1 is provided with a wall 5 to surround a space 3 for containing a utensil placing bed 2 with a vibration resisting protection function and form an endothermic agent filling part. The wall 5 is provided with a ceiling wall 11, a double side wall 12, and a double bottom wall 13, and an internal space surrounded with the ceiling wall 11, the double side wall 12, and a double bottom wall 13 forms the endothermic agent filling part. The endothermic agent filling part is filled with an endothermic agent.