To reduce the number of part items constituting a reservoir and manufacturing operations and costs while attaching importance to the appearance and design of the reservoir.

The reservoir 15 attached to the end of a handle bar 1 has a planar shape such that its front vehicle body side portion and its rear vehicle body side portion are asymmetrical while the right and left sides of the handle bar 1 across the longitudinal centerline of the body of the bar-handled vehicle are symmetrical. One side of a diaphragm plate 34 and the other side of a diaphragm 35, disposed respectively in upper and lower positions and sandwiched between a reservoir body and a cap, can mate with each other in the manner of a tongue-and-groove joint. Even when the diaphragm plate 34 and the diaphragm 45 are inverted, the other side of the diaphragm plate 34 and the one side of the diaphragm 35 can mate with each other in the manner of a tongue- and-groove joint.