We conducted performance tests on a polymer electrolyte membrane fuel cell containing a catalyst-coated membrane in which artificial pinholes were introduced. The membrane electrode assembly (MEA) with the punctured membrane showed similar performance behavior to an unblemished MEA in the lower current density region. However, the performance of the pinhole MEA with the punctured membrane in the higher current density region was inferior and unstable. The structures of the defective membrane and the MEA were analyzed by field-emission scanning electron microscopy, and their electrochemical characteristics were investigated by electrochemical impedance spectroscopy and single-cell testing.