PURPOSE: To accelerate warming up with a simple structure, by throttling an exhaust regulating valve in utilization of hydrogen equilibrium pressure in a metal hydride in a hermetically sealed vessel.

CONSTITUTION: A metal hydride is filled up in a temperature sensing cylinder 1, and a stainless steel bellows 3 is interconnected to this. And, a butterfly valve 6 is installed in an outlet of an exhaust pipe 5, and it is energized so as to close the exhaust pipe by a spring, while a tip of the bellows 3 is connected to a shaft 7. The butterfly valve 6 is closed by the spring till an engine is warmed up and thereby warming up is accelerated, and when temperature in the exhaust pipe goes up, the valve 6 is opened by the bellows 3. With this constitution, the warming up is accelerable with a simple structure.