Abstract: A check valve of one embodiment includes a spout member which has a flow path inside, an urging member supported by an inner end portion of the spout member, a valve body connected to the urging member, and a cylindrical member having a flow path inside, and is provided with a valve seat portion on an inner circumferential face, the spout member is fixedly attached to the cylindrical member so that the valve body and the urging member are inserted into the cylindrical member and the valve body is urged to the valve seat portion by the urging member, and the flow path and the flow path communicate with each other to configure an outflow path through which the content in the vessel flows out.