A canister includes a partition wall which extends toward the lid member with one end thereof connected to the end wall and opposite sides are connected to an inner surface of the casing body. First and second adsorbent layers, formed by an adsorbent, are retained between first and second filters and a third filter, respectively. The first and second filters are fixedly disposed on opposite sides of the partition wall to define first and second chambers between the first and second filters and the end wall, respectively. The third filter is placed and carried on an inner surface of a support plate which is fitted in the casing body and which has a large number of communication bores. The support plate and a lid member are biased by a spring in a direction to compress the first and second adsorbent layers. An inclination inhibiting portion is provided on at least one of the casing body and the partition wall on the opposite side from the third chamber with respect to the third filter and the support plate at a distance from the third filter which substantially corresponds to a distance between the third filter and the partition wall. Thus, it is possible to prevent a reduction in adsorbing efficiency by preventing the third filter and support plate from inclining.