A suction device includes a valve, a piezoelectric pump, and a housing. The valve includes a valve casing and a diaphragm. A first ventilation hole, a second ventilation hole, and a third ventilation hole are formed in the valve casing. The diaphragm is fixed to the valve casing and forms a flow path in the valve casing. The second ventilation hole is opened under atmospheric pressure. The piezoelectric pump has a suction hole and a discharge hole. The discharge hole is in communication with the first ventilation hole. The housing has a cavity. A suction pad is attached to the cavity. The housing forms an enclosed space together with the valve and the piezoelectric pump. The enclosed space is a space that is in communication with the cavity, the suction hole, and the third ventilation hole.