A fuel vapor leak check module has a pump discharging an air through an outlet. When the fuel vapor check module is mounted on a vehicle, an outlet of the pump is opened downwardly in the gravity direction. A housing has an opening provided above the outlet. The foreign particles discharged from the outlet of the pump are deposited on the inner surface of the housing. The foreign particles hardly reach to the opening even if the discharged air pushes up the foreign particles. Thus, the foreign particles are separated from the discharged air by the gravity to avoid the scatter thereof.