An evaporated fuel processing apparatus includes a casing provided with a tank port, and the casing is provided with at least one adsorbent layer filled with adsorbent which adsorbs/desorbs evaporated fuel generated in a fuel tank or the like, a vapor-liquid separator separating the evaporated fuel introduced from the tank port into a vapor phase component and a liquid phase component thereof, respectively, and a filter separating the vapor-liquid separator from the adsorbent layer, and, a liquid storing member which is a component separate from the casing, and is opened at at least a tank port side for storing the separated liquid phase component is attached in the casing, and, the filter is fixed to an inner circumferential surface of the casing and the liquid storing member is sandwiched between the casing and the filter.