An evaporated fuel collecting apparatus comprises a canister containing an adsorbent for collecting evaporated fuel (vapor) generated in a fuel tank, an inflow port, a purge port, and an atmospheric port, which are formed in the canister. The inflow port is used to introduce the vapor generated in the furl tank into the canister. The purge port is used to purge the vapor collected in the canister. The atmospheric port is used to introduce atmospheric air into the canister. The canister is provided with a photocatalyst device including a photocatalyst for oxidatively decompose the vapor when exposed to light irradiation and an ultraviolet LED which irradiates light to the photocatalyst. The photocatalyst device is disposed in correspondence with the atmospheric port.