The present invention relates to a fuel cell including: a membrane electrode assembly 10 having an electrolyte membrane 17 sandwiched by a fuel electrode 13 and an air electrode 16; a fuel supply part 43 disposed on the fuel electrode side of the membrane electrode assembly to supply a fuel to the fuel electrode 13; a fuel storage part 41 storing the fuel; and a fuel channel 44 leading the fuel stored in the fuel storage part to the fuel supply part. Since a fuel cell can generate electricity for a long time by being continuously supplied with a fuel, the fuel cell serves as a system advantageous as a power source of a portable electronic device such as a portable phone if it can be made compact. Here, if a user keeps touching a high-temperature portion of the fuel cell, he/she may suffer from low-temperature burn or the like, and therefore, some measure such as providing a heat insulator is necessary, but sufficient heat insulation results in excessively large weight and volume, which leads to a problem that the fuel cell is not suitable as a power source of a portable electronic device. The present invention solves the above problem by the structure in which the fuel channel 44 in the fuel cell is formed as a channel heating the fuel by heat generated in the air electrode and leading the heated fuel to the fuel supply part.