A hydrogen purification/compression apparatus for producing, from hydrogen-containing gas, purified hydrogen gas, wherein the pressure and the purity of the purified hydrogen gas are increased by a plurality of stacked cell structures, the apparatus comprising: a plurality of stacked cell structures; and a pressing structure configured to apply a clamping stress in a stacking direction of the cell structures, wherein each of the cell structures comprises: a polymer electrolyte membrane; an anode catalyst layer stacked on one side of the polymer electrolyte membrane; a cathode catalyst layer stacked on the other side of the polymer electrolyte membrane; an anode-side power feeder disposed outside the anode catalyst layer so as to be opposite to the anode catalyst layer; a cathode-side power feeder disposed outside the cathode catalyst layer so as to be opposite to the cathode catalyst layer; an anode-side separator disposed outside the anode-side power feeder so as to be opposite to the anode-side power feeder and having a passage through which the hydrogen-containing gas is supplied; and a cathode-side separator disposed outside the cathode-side power feeder so as to be opposite to the cathode-side power feeder and having a passage through which the purified hydrogen gas is discharged, wherein a sealing portion between the cell structures comprises: a gasket; a pair of opposite flat portions formed on the anode-side separator and the cathode-side separator in order to press the gasket; and an annular protrusion having one layer or a plurality of adjacent layers formed on both or either of the pair of the flat portions, and the one annular protrusion or the adjacent annular protrusions compresses and presses the gasket between protrusions. a plurality of stacked cell structures; and a pressing structure configured to apply a clamping stress in a stacking direction of the cell structures, wherein each of the cell structures comprises: a polymer electrolyte membrane; an anode catalyst layer stacked on one side of the polymer electrolyte membrane; a cathode catalyst layer stacked on the other side of the polymer electrolyte membrane; an anode-side power feeder disposed outside the anode catalyst layer so as to be opposite to the anode catalyst layer; a cathode-side power feeder disposed outside the cathode catalyst layer so as to be opposite to the cathode catalyst layer; an anode-side separator disposed outside the anode-side power feeder so as to be opposite to the anode-side power feeder and having a passage through which the hydrogen-containing gas is supplied; and a cathode-side separator disposed outside the cathode-side power feeder so as to be opposite to the cathode-side power feeder and having a passage through which the purified hydrogen gas is discharged, a polymer electrolyte membrane; an anode catalyst layer stacked on one side of the polymer electrolyte membrane; a cathode catalyst layer stacked on the other side of the polymer electrolyte membrane; an anode-side power feeder disposed outside the anode catalyst layer so as to be opposite to the anode catalyst layer; a cathode-side power feeder disposed outside the cathode catalyst layer so as to be opposite to the cathode catalyst layer; an anode-side separator disposed outside the anode-side power feeder so as to be opposite to the anode-side power feeder and having a passage through which the hydrogen-containing gas is supplied; and a cathode-side separator disposed outside the cathode-side power feeder so as to be opposite to the cathode-side power feeder and having a passage through which the purified hydrogen gas is discharged, wherein a sealing portion between the cell structures comprises: a gasket; a pair of opposite flat portions formed on the anode-side separator and the cathode-side separator in order to press the gasket; and an annular protrusion having one layer or a plurality of adjacent layers formed on both or either of the pair of the flat portions, and the one annular protrusion or the adjacent annular protrusions compresses and presses the gasket between protrusions. a gasket; a pair of opposite flat portions formed on the anode-side separator and the cathode-side separator in order to press the gasket; and an annular protrusion having one layer or a plurality of adjacent layers formed on both or either of the pair of the flat portions, and the one annular protrusion or the adjacent annular protrusions compresses and presses the gasket between protrusions.