An electrode structure 15 is accommodated in a joint portion of frames 13 and 14. A first gas diffusion layer 19 and a first gas passage forming member 21 are laid on a first surface of the electrode structure 15, and a second gas diffusion layer 20 and a second gas passage forming member 22 are laid on a second surface of the electrode structure 15. A separator 23 is joined to surfaces of the frame 13 and the gas passage forming member 21, and a separator 24 is joined to surfaces of the frame 14 and the gas passage forming member 22. A porous layer 26 having continuous pores is located between the gas passage forming member 22 and the separator 24. A drainage promoting member 30 formed of a porous material having continuous pores is provided to communicate with a downstream end of a second gas passage T2 of the second gas passage forming member 22 and to communicate with a downstream end of the continuous pores of the porous layer 26. Generated water that has been drawn into the porous layer 26 from the second gas passage T2 by capillary action flows downstream by surface tension of water, and is then drawn into the drainage promoting member 30. The water drawn in by the drainage promoting member 30 is discharged into a discharging passage by fluid pressure of oxidation off-gas that flows from the second gas passage T2 into the continuous pores of the drainage promoting member 30. Accordingly, a fuel battery is provided in which generated water is prevented from remaining in the second gas passage T2 of the cathode side second gas passage forming member 22, and it is possible to prevent the power generation performance from being lowered by insufficient supply of oxidation gas to the electrode structure 15.