A hydrogen gas visualization device comprises a hydrogen sensor having a thin film layer formed on the surface of a substrate and a catalyst layer formed on the surface of the thin film layer which, when contacted by hydrogen gas contained in an atmosphere, hydrogenates the thin film layer and thereby changes the optical reflectance of the thin film layer, and one or more sensor faces provided with the hydrogen sensor. The hydrogen gas visualization device visualizes, on the sensor faces, the distribution of hydrogen gas contained in the atmosphere contacting the hydrogen sensor and thereby visualizes the existence and flow of the hydrogen gas.