To provide a rotary stopper for a mixing water faucet with single lever to which a stopper mechanism can be easily attache later.

The rotary stopper for a mixing water faucet with single lever is provided with a casing comprising a small-diameter cylinder, a large-diameter cylinder, and a ring connecting one end of the small-diameter cylinder and one end of the large-diameter cylinder; a disk type valve mechanism housed in the large-diameter cylinder of the casing; a valve mechanism drive rod extending outside the casing through other end of the small-diameter cylinder; a projection formed on an inner periphery of the small-diameter cylinder of the casing at the other end for a disk type valve unit for a mixing water faucet with a single lever having a lever guide, in which the valve mechanism drive rod is inserted in a relatively oscillatory but non-rotatable state, and the lever guide is rotatably supported by the small-diameter cylinder; and a connecting face with the projection formed on the lever guide.