NOVELTY - Pressure swing adsorption (PSA) apparatus comprises: an adsorption tower (1); an adsorbent bed (2) in the tower; a carbon monoxide adsorbent layer (5); a carbonaceous adsorbent layer (4) for adsorbing carbon dioxide; and a zeolite layer (3a) for adsorbing nitrogen and/or an adsorbent layer for adsorbing argon in random order in the direction from the upstream side to the downstream side of passage of the hydrogen-containing gas, where during the regeneration of the adsorbent bed, a purge gas is passed through in the direction opposite to the passage of the hydrogen-containing gas.    USE - The PSA apparatus is useful for high-purity hydrogen gas production by removing carbon monoxide, carbon dioxide, nitrogen and/or argon by adsorption from a hydrogen-containing gas. The produced hydrogen gas is useful for fuel cell.    ADVANTAGE - The PSA apparatus can recover high-purity hydrogen gas at a high recovery rate from a reformed gas (hydrogen-containing gas containing carbon monoxide, carbon dioxide, nitrogen and argon as impurities) produced by a reforming process e.g. an auto-thermal reforming process, with a lower degree of vacuum and a smaller purge gas amount in the regeneration operation. The PSA apparatus has reduced equipment size, hence reducing the equipment cost.    DETAILED DESCRIPTION - Pressure swing adsorption (PSA) apparatus comprises: an adsorption tower (1); an adsorbent bed (2) in the tower; a carbon monoxide adsorbent layer (5) for selectively adsorbing carbon monoxide gas without substantial adsorption of carbon dioxide, nitrogen and/or argon; a carbonaceous adsorbent layer (4) for adsorbing carbon dioxide; and a zeolite layer for adsorbing carbon monoxide, a zeolite layer (3a) for adsorbing nitrogen and/or an adsorbent layer for adsorbing argon in random order in the direction from the upstream side to the downstream side of passage of the hydrogen-containing gas, where during the regeneration of the adsorbent bed, a purge gas is passed through in the direction opposite to the passage of the hydrogen-containing gas.    DESCRIPTION OF DRAWING(S) - The figure shows a schematic representation of an adsorption tower in a PSA apparatus.    Adsorption tower (1)    Adsorbent bed (2)    Nitrogen adsorbing zeolite layer (3a)    Carbonaceous adsorbent layer (4)    Carbon monoxide adsorbent layer (5)