FUEL CELL UNIT

A fuel cell unit includes: a first case housing a fuel cell stack; a second case housing a power converter; an adapter fixing the first and second cases together; and a conductive member connecting between the fuel cell stack and the power converter. A first flange portion, surrounding a first opening portion, of the first case and a second flange portion, surrounding a second opening portion, of the second case are different in at least one of shape and size. The adapter includes: a third flange portion corresponding to the first flange portion; a fourth flange portion corresponding to the second flange portion; a surrounding wall portion continuous from the third flange portion to the fourth flange portion to define an internal space communicating with openings inside the third and fourth flange portions; and a partition wall portion between the first opening portion and the second opening portion.