PURPOSE: To remove safely and efficiently mixed fine powder of a metal hydride, by mixing a hydrogen stream containing the fine powder of the metal hydride with a small amount of air, etc., inactivating the fine powder of the metal hydride, and capturing the inactivated fine powder of the metal hydride with a magnetic filter.

CONSTITUTION: A hydrogen stream containing fine powder of a metal hydride is introduced from a hydrogen tank 1 containing the metal hydride occluding and releasing hydrogen through an inlet pipe 2 into a gas mixer 3 and mixed with air or a waste gas containing oxygen or carbon monoxide in a small amount (in an amount limited to keep the mixture with the metal hydride below the explosion limit) introduced from an injection pipe 4 to inactivate the fine powder of the metal hydride. The inactivated fine powder of the metal hydride is then adsorbed on a magnetic filter 5 and removed, and the resultant hydrogen stream is fed through an outlet pipe 6 to an apparatus utilizing the hydrogen gas, e.g. a hydrogen engine.