CANISTER

A canister includes at least one chamber in which an adsorbent to adsorb fuel vapor is arranged, an inflow port, an atmosphere port, an outflow port, and an adsorbent agglomerate. The adsorbent agglomerate is arranged in a specific chamber. The adsorbent agglomerate is a mass of a fibrous adsorbent. The specific chamber is one of the at least one chamber. The adsorbent agglomerate includes, on its outer surface, first and second surfaces intersecting with a flow direction of a fluid, and the second surface is positioned on a side opposite to the first surface. The adsorbent agglomerate includes at least one vacant space formed in the first surface and/or the second surface, and the at least one vacant space extends along the flow direction to a bottom located inside the adsorbent agglomerate.