To reduce size and weight of canister while improving adsorbing/desorbing performance by optimizing adsorbent that fills chamber located at air release side.Adsorbent filling chambers 8, 9 located at air port 5 side, of a plurality of chambers 5˜8 that are arranged in series along an air flow direction in case 2, is formed by macroscopic pore whose diameter is 50 nm or greater. The adsorbent has hollow cylindrical shape whose inside thickness is 0.6 to 1.5 mm and whose outside diameter is 4 to 6 mm or hollow spherical shape whose inside thickness is 0.6 to 1.5 mm and whose diameter is 4 to 6 mm. A ratio of volume of the macroscopic pore whose diameter is less than 500 nm to total volume of the macroscopic pore whose diameter is equal to or greater than 50 nm is within a range of 30 to 70%.