Check valve

A check valve comprising:

• a base member provided with an inlet channel along which fluid flows in one direction;
• a valve unit disposed on a valve mounting surface defined on one of the faces of the base member and operative to open and close the inlet channel in response to the pressure of fluid;
• and
• a valve seating surface defined on the valve mounting surface at the periphery of the opening of the inlet channel,
• wherein the valve unit comprises:
• a film valve body configured to be in contact with the valve seating surface or to be separated from the valve seating surface;
• and
• a frame body on which the film valve body is tightly stretched,
• wherein one or more communicating grooves are formed on the valve mounting surface across the frame body so as to extend from the valve seating surface to the outside of the frame body,
• wherein the inlet channel is blocked by the film valve body when the film valve body is in contact with the valve seating surface, and
• wherein the inlet channel and the outside of the frame body are communicated via the communicating grooves when the film valve body is separated from the valve seating surface.