A gas passage forming body for a fuel battery includes gas passages and water guide passages. A communication passage is arranged between one of the water guide passages and a gas passage that is adjacent to the water guide passage and is in communication with the adjacent gas passage and water guide passage to permit water to move therethrough. An aid portion is arranged at water drainage ends of two adjacent ones of the water guide passages and aids bonding of water drained from the water drainage ends of the two adjacent ones of the water guide passages. Thus, water drainage from the water guide passages of the gas passage forming body is improved, and water in the gas passages is reduced. As a result, the battery performance of the fuel battery is improved due to an improvement in gas diffusion.