During the durability tests for PEMFC membranes, performance characterization is conducted to determine the degree of degradation, the interval for which is different for each durability test protocol. Before performance characterization, activation is carried out to determine the reliability. Most activations are accompanied by voltage changes, which can lead to electrode degradation. However, this has largely been neglected because the activation time is shorter than the durability test time. In this study, activation was conducted at 24, 48, and 144 h intervals, during the membrane durability test of a PEMFC, and the effect of activation on the degradation of the membrane and electrode was investigated. For a shorter activation interval during the durability test, the lifetime of the membrane was reduced by up to 35%. For the same durability test time, more activations led to greater electrode and membrane degradation. Through scanning electron microscopy/energy-dispersive X-ray spectroscopy (SEM-EDS) analysis, it was found that for a shorter activation interval, more Pt was deposited into the membrane and then the membrane was thinner. During the durability test, frequent activation accelerated membrane and electrode degradation.