Abstract: A master cylinder apparatus for a vehicle is adapted to be attached to a bar type steering handle. This master cylinder apparatus comprises a master cylinder attached directly or via a bracket to the bar type steering handle, an operating level pivoted on the bracket or a lever bracket of the master cylinder by means of a support shaft, an adjust bolt provided thrustable forward and backward to the operating lever, and a push rod having one end abutting on the rear end of a piston in the master cylinder and the other end pivoted on a free end of the adjust bolt. The forward/backward thrusting movement of the adjust bolt alters the distance between the support shaft and the point of action of the operating lever to the push rod, thereby changing the lever ratio of the operating lever to provide the operational feeling desired by a rider.