Abstract: A fuel cell unit comprises a fuel cell body, a case and a seal member. The fuel cell body has a membrane electrode assembly for generating power, which comprises an anode being supplied with fluid fuel, a cathode being exposed to atmosphere to be supplied with an oxydant, a membrane sandwiched between the anode and cathode, and a fuel tank connected to a fuel cartridge, from which the liquid fuel is supplied to the anode. The case has an internal space for accommodating an electronic part, the case enclosing and holding the fuel cell body and having an opening in the area of the cathode of the membrane electrode assembly and opened to the outside. The seal member for providing a seal is disposed between the edges surrounding the opening in the case and the fuel cell body to shield the internal space from the opening.