Conventional hydrogen purification apparatuses cannot be used satisfactorily for applications in which much time is required for startup of the apparatus, and the apparatus is repeatedly started and stopped at frequent intervals because of complicated handling. In a hydrogen purification apparatus comprising at least a catalysis body removing carbon monoxide from a reformed gas containing hydrogen, carbon monoxide and steam, the catalyst body is constituted by a carrier comprised of a complex oxide in which at least one of Mo, W and Re is compounded with Zr, or comprised of an oxide of one of Mo, W, Re and Zr, and at least one of Pt, Pd, Rh and Ru carried on the surface of the carrier.