Liquid water growth pattern in the gas flow channel in PEFC was visualized by using an ex-situ optical cross-sectional observation system developed. We investigated the impact of surface hydrophobicity of the GDL and channel on the liquid water growth pattern. The liquid water, which was emerged at 5 mm back from the gas outlet, was observed with spatial resolution of 20 μm by optimizing the optical system including CCD camera. Pressure drop through the channel was measured to evaluate the impact of water droplet on it. As a result, it is obtained that adhesion force formed in combination of hydrophobic GDL and hydrophilic channel sucked the water from GDL to channel corner, and suppressed the water contact with the GDL surface, and accelerated the water drainage, leading to prevent the water droplet growing in the channel.