A valve body of each of low and high-pressure couplers is urged in a close direction in to a supply side of a partition. A stem that penetrates through an opening portion and projects into the receive side is connected to the valve body. A cylinder portion is formed on the receive side of the partition. A locking mechanism is provided in a vicinity of an end portion of the cylinder portion. A movable sleeve having an annular projecting portion is provided on an inside of the cylinder portion. Each of low and high-pressure plugs has an annular projecting surface that can engage with the annular projecting portion, a flange that engages with an end portion of the cylinder portion, and an engaging portion that can engage with the locking mechanism.