A valve device includes a valve main body having a valve chamber, and inflow and outflow passages communicating with the valve chamber; an annular valve seat surrounding an opening from the inflow passage to the valve chamber; and a valve element moved to contact with and separate from the valve seat. One of the valve seat and the valve element includes a contact surface, and the other of the valve seat and the valve element includes an annular raised rib. The rib has at a top thereof an annular sealing part contacting the contact surface to provide sealing between the valve element and the valve seat. The sealing part includes an annular flat surface extending parallel to the contact surface, and two annular inclined surfaces provided adjacent to the flat surface on both sides and inclined to the flat surface to extend in a direction away from the contact surface.