The polymer electrolyte fuel cell (PEFC) is a promising candidate for mobile and vehicle applications and distributed power systems due to its high power density and low operation temperature. However, water flooding in the cathode gas diffusion layer (GDL) is one of the critical barriers to high performance operation, because liquid water condensed in the porous GDL blocks oxygen transport to the active reaction sites. In this study, we observed removal behavior of condensed water in a porous electrode of PEFC using a microscope and discuss its fundamental characteristics. Furthermore, in order to prevent water flooding and improve cell performance, a slit was introduced into the cathode GDL. With this cathode structure, it was found that water removal is promoted, and cell voltage and power density are increased at a high current density.