A check valve includes a tubular valve seat frame, a valve seat that is fixedly secured to the inside of the valve seat frame and has a communication hole through which a working fluid flows, and a valve body that is on the working fluid outflow side of the valve seat for opening and closing the valve seat. The valve seat frame, the valve seat, and the valve body are put into one unit so that the check valve has a simple structure and a good assembly property, and can be manufactured at low cost. The check valve is included, whereby a small, durable, and high-performance pump can be provided.