Adsorbent, Canister and Method for Producing Adsorbent

An adsorbent to be packed into a canister, at least containing activated carbon and an additive material that has a higher heat capacity than the activated carbon. The adsorbent has first pores derived from the activated carbon that are less than 100 nm and second pores derived from meltable cores that are 1 μm or more. The adsorbent is in the form of a hollow molded body having an outer diameter of more than 6 mm and not more than 50 mm and including a cylindrical wall and honeycomb walls each having a thickness of not less than 0.2 mm and not more than 1 mm. The adsorbent has a volumetric specific heat of 0.08 kcal/L·° C. or more. The ratio of the volume of the second pores to the volume of the first pores is not less than 10% and not more than 200%.