A self-weight pressure control valve includes a hollow case main body with an opening, a partitioning wall dividing the case main body into first and second pressure chambers in communication with the opening, a communication opening in the partitioning wall and communicating the first pressure chamber and the second pressure chamber to each other, a valve rod including a rod portion inserted through the communication opening to pass the partitioning wall, and a valve portion located in the first pressure chamber, and a pressure sensitive film covering the opening of the case main body, coupled with a tip of the rod portion of the valve rod, and flexibly deformable toward the rod portion. When the pressure sensitive film is not flexibly deformed toward the rod portion, the communication opening is maintained in a closed state by the valve portion by use of a self-weight of the valve rod.