A canister includes a canister case having an adsorbent chamber, an adsorbent housed in the adsorbent chamber of the canister case, a filter disposed between the adsorbent chamber and a port mounted on an end wall of the adsorbent chamber, and a tentative filter engaging projection provided in the adsorbent chamber. The filter is loosely fitted within the adsorbent chamber and then welded on the end wall of the adsorbent chamber. The tentative filter engaging projection tentatively holds the filter loosely fitted within the adsorbent chamber in a welding step of the filter.