PURPOSE: To save fuel in a heat source device for air conditioning by oppositely disposing metallic containers wherein metallic hydrides having different characteristics are separately contained and sucking and discharging hydrogen by the effects of waste heat of an engine and air.

CONSTITUTION: When water heated by waste heat of an engine 1 is fed into a heat-exchange pipe 10 to heat a metallic hydride 6 inside a metallic container 2, high pressure hydrogen gas is discharged to pass through a valve 18 into a container 4 and then occluded to metallic hydride 8 therein. The occlusion heat is discharged to a blast passage 26 by a fan 22. When valves 13, 18 are closed and the container 2 is cooled by a fan 20, a pressure in the container 4 is reduced and a pressure in the container 2 gets lower than that in the container 4 because of difference in characteristics of metallic hydrides 6, 8. When the valve 18 is opened, a hydrogen gas is fed into the container, while taking radiant heat from air. Hence, if a damper 28 is switched, cool air is supplied into the blast passage 26 to perform cooling. On the other hand, the other containers 3, 5 form a reverse cycle to be fed with cooling air.