A gas control device includes a first pump, a second pump, and a connection casing. The first pump includes a first pump casing, a first suction hole, and a first discharge hole. The first pump casing has a plurality of outer walls. The second pump includes a second pump casing, a second suction hole, and a second discharge hole. The connection casing has a first opening and a second opening. The connection casing forms, together with the first pump casing and the second pump casing, a first closed space. The second discharge hole and the first suction hole communicate with each other via the first closed space. The first pump and the second pump are connected in series with each other. The outer wall in which first suction hole is provided faces the first closed space.