A fuel cell comprising: a membrane electrode assembly (30, 50) formed by joining an anode to one surface of an electrolyte membrane and joining a cathode to another surface of the electrolyte membrane; a frame body formed integrally with the membrane electrode assembly (30, 50); manifold portions on both outer sides of the membrane electrode assembly (30, 50) in the cell longitudinal direction (β) for supplying and discharging a hydrogen-containing gas and an oxygen-containing gas; and a pair of separators (40, 41, 60, 61) holding the membrane electrode assembly (30, 50) and the frame body therebetween, wherein a diffuser portion which is a flow region for a hydrogen-containing gas or an oxygen-containing gas is formed between the frame body and each of the pair of separators (40, 41, 60, 61), in regions between the manifold portions and the membrane electrode assembly (30, 50), at least one pair of holding pieces (42, 43, 62, 63) holding the membrane electrode assembly (30, 50) therebetween are formed in the pair of separators (40, 41, 60, 61), and positions of holding end portions (42a, 43a, 62a, 63a) of the pair of holding pieces (42, 43, 62, 63) are offset from each other in a plane direction of the membrane electrode assembly (30, 50) and one of the holding end portions (42a, 62a) of one holding piece (42, 62) of the pair of holding pieces (42, 43, 62, 63) is located at a position facing a gas flowing passage of the corresponding diffuser portion formed between the frame body and the separator (41, 61) in which the other holding piece (43, 63) of the pair of holding pieces (42, 43, 62, 63) is formed. a membrane electrode assembly (30, 50) formed by joining an anode to one surface of an electrolyte membrane and joining a cathode to another surface of the electrolyte membrane; a frame body formed integrally with the membrane electrode assembly (30, 50); manifold portions on both outer sides of the membrane electrode assembly (30, 50) in the cell longitudinal direction (β) for supplying and discharging a hydrogen-containing gas and an oxygen-containing gas; and a pair of separators (40, 41, 60, 61) holding the membrane electrode assembly (30, 50) and the frame body therebetween, wherein a diffuser portion which is a flow region for a hydrogen-containing gas or an oxygen-containing gas is formed between the frame body and each of the pair of separators (40, 41, 60, 61), in regions between the manifold portions and the membrane electrode assembly (30, 50), at least one pair of holding pieces (42, 43, 62, 63) holding the membrane electrode assembly (30, 50) therebetween are formed in the pair of separators (40, 41, 60, 61), and positions of holding end portions (42a, 43a, 62a, 63a) of the pair of holding pieces (42, 43, 62, 63) are offset from each other in a plane direction of the membrane electrode assembly (30, 50) and one of the holding end portions (42a, 62a) of one holding piece (42, 62) of the pair of holding pieces (42, 43, 62, 63) is located at a position facing a gas flowing passage of the corresponding diffuser portion formed between the frame body and the separator (41, 61) in which the other holding piece (43, 63) of the pair of holding pieces (42, 43, 62, 63) is formed.