Unit cells and separator elements are stacked in layers, thus constituting a stacked structure of a fuel cell. A first segment channel, which is bored through the peripheral region of each separator element, communicates with a second segment channel formed in a cylindrical seal member which is joined to each two adjacent separator elements. Thus, manifolds for the intake and exhaust of a fuel gas and an oxidant gas are defined. The cylindrical seal member includes a pair of ring-shaped metal members joined to each two adjacent separator elements and a ring-shaped insulating member interposed between the metal members. Thus, the gases in the manifolds can be prevented from leaking out, and the adjacent separator elements are insulated from one another.