A fuel cutoff valve is provided with a casing that forms a valve chamber that is connected to a connection conduit, a float mechanism that is housed so as to be able to rise and fall in the valve chamber, and a spring that supports the float mechanism. The float mechanism is structured through an assembly of a first float body and a second float body, where the first float body is provided with a valve portion that opens and closes the connection conduit and provided with a storage chamber that is open on the bottom, where the second float body is housed in the storage chamber to be assembled into the first float body.