An actuator unit for a hydraulic brake mechanism on two-wheelers, comprising a housing fastened to the handlebar, a brake cylinder being arranged substantially perpendicular to the handlebar in the housing, a piston movable in it and a brake lever acting on the piston at an intermediate portion remote from either end of the lever, the lever being mounted at one end thereof to rotate relative to the housing, wherein the brake lever is mounted adjustably movable with respect to an axis substantially at an end of the lever, the axis being unchangeable in position but rotatably mounted to the housing, the adjustment option being provided for by the adjustment mechanism, wherein the lever, the adjustment mechanism and the axis rotate together relatively to the housing upon operation.