A hydrogen purifier (100) includes: a shift conversion catalyst (5a) which reduces, through a shift reaction, carbon monoxide contained in a hydrogen-containing gas; and a methanation catalyst (6a) which reduces, through a methanation reaction, carbon monoxide contained in the hydrogen-containing gas that has passed through the shift conversion catalyst (5a). The shift conversion catalyst (5a) and the methanation catalyst (6a) are heat exchangeable with each other via a first partition wall (8), and a flow direction of the hydrogen-containing gas that passes through the shift conversion catalyst (5a) is opposite to a flow direction of the hydrogen-containing gas that passes through the methanation catalyst (6a).