A fuel cell unit includes: an ammonia pump including a pump cell that reduces an amount of ammonia in fuel gas; and a fuel cell including a power generation cell that is supplied with oxidant gas and the fuel gas. Each of the pump cell and the power generation cell has: a membrane electrode gas diffusion layer assembly; a first separator and a second separator; and a first gas channel and a second gas channel. In each of the pump cell and the power generation cell, the first gas channel and the second gas channel are formed such that an amount of pressure loss in the first gas channel is smaller than an amount of pressure loss in the second gas channel.