Abstract: The present invention relates to: a fuel cell which includes a stack part (21) formed by stacking a membrane electrode assembly and a separator, and in which the membrane electrode assembly and the separator each include a communication passage part to form a communication passage for allowing fuel gas or oxidant gas to flow, the communication passage formed by the communication passage parts is opened at a positive end portion and a negative end portion of the stack part (21), and one end of the communication passage is sealable; and a method and an apparatus for assembling the fuel cell. The fuel cell has a problem of not being easy to manufacture, for example. This is because positive and negative polarities of the fuel cell are determined when the stack is assembled; to dispose stacks having the same configuration with their polarities inverted, the stack whose polarities are inverted and the stack whose polarities are not inverted need to be assembled individually.