A tank passage communicates a canister housing with a fuel tank. A purge passage communicates the canister housing with an intake air system. An atmospheric air passage communicates the canister housing with an atmosphere. A valve housing accommodating a valve element is located in a recessed portion defined with a first inner wall and a second inner wall. A seal member is located on a radially outside of the valve housing to seal the recessed portion. The first inner wall has a first opening to communicate the canister housing with the recessed portion. The second inner wall has a second opening to communicate the recessed portion with the atmospheric air passage. The first opening or the second opening is defined around a valve seat. The valve element is seated on and lifted from the valve seat to control communication between the canister housing and the atmospheric air passage.