Lever holders 14a, 14a are provided to a cylinder body 14 attached to a bar handle 12 and hinged portions 32c and 33a of a lever body 32 which is one rotation member and an interlocking member 33 which is the other rotation member are pivotally supported by the lever holders 14a and 14a. Stopper portions 32e, 33e are disposed to protrude from the hinged portions 32c, 33a. The stopper portion 33e of the interlocking member 33 is allowed to abut on a stopper abutting surface 14b provided in the cylinder body 14. The stopper abutting surface 14b is formed perpendicular to the axial line of the bar handle 12 and the side of the cylinder body opposite to the bar handle is provided integrally with a front cover wall portion 14c which covers the abutting portion between the stopper portion 33e and the stopper abutting surface 14b.