To provide a polymer electrolyte fuel cell that can exhibit an excellent power generation performance even under a condition of high-temperature and low-humidification.

Disclosed is a carbon sheet having short carbon fibers bound with carbon, the carbon sheet being a gas diffusion layer for a polymer electrolyte fuel cell having a standard deviation of pressure distribution between 0.8 MPa and 1.6 MPa obtained by a compression test comprising the steps of: making a sample piece in a circular form having a diameter of 25 mm from a gas diffusion layer for a polymer electrolyte fuel cell to be tested; applying a surface pressure of 2 MPa to the sample piece with a piece of pressure sensitive paper being interposed; keeping the pressure for two minutes; analyzing the pressure sensitive paper by a scanner and an analysis software (FPD9270 produced by Fujifilm Corporation); obtaining outputs of the compression data at each divided point of the area to be analyzed; and calculating a standard deviation of the pressure distribution of the load.