Apparatus for uniformizing light amount distribution by shaking line beams along a longitudinal axis direction is provided. The apparatus includes a mirror mount, a mirror, an actuator, and a deformation member. The mirror fixed to the mirror mount and includes a reflective surface. The actuator is disposed at a distance from the mirror mount and configured to repeat expansion and contraction along a first direction. The deformation member includes a plurality of blocks connected to each other by flexible joints and is coupled to the actuator and the mirror mount. The deformation member is configured to change a displacement in the first direction due to operation of the actuator to a displacement in a second direction that crosses the first direction, amplify the changed displacement, and transmit the amplified displacement to the mirror mount.