Polymer electrolyte fuel cell

Disclosed is a solid polymer fuel cell which is improved in durability by suppressing decomposition and deterioration of the polymer electrolyte. Specifically disclosed is a polymer electrolyte fuel cell comprising a membrane electrode assembly having an anode, a cathode arranged opposite to the anode and a polymer electrolyte membrane arranged between the anode and the cathode; and a pair of separator plates which are arranged opposite to each other while having the membrane electrode assembly interposed therebetween and provided with an anode-side gas channel for supplying a fuel gas to the anode and a cathode-side gas channel for supplying an oxidant gas to the cathode. The anode catalyst layer contains at least one electrode catalyst selected from the group consisting of Pt particles and Pt alloy particles having a particle size of 6-10 nm. The anode catalyst layer has a thickness of 1-5 mu m, and the volume density of Pt in the anode catalyst layer is 1-5 g/cm3, and The cathode catalyst layer has a thickness of more than 10mu m, and the volume density of Pt in the anode catalyst layer is 0.1-0.5 g/cm3.