PURPOSE: To prevent a lens from being strained or broken when aligned.

CONSTITUTION: A movable ring 3 is provided movably in the vertical direction at the outer periphery of a lens mount base 1 where the lens 2 to be aligned is mounted. A fixation ring 4 is provided at the outer periphery of the movable ring 3. The fixation ring 4 is provided with a rack 8, which engages a gear part 3c provided at the outer periphery of the movable ring 3, which is moved vertically by the movement of the rack 8. Comic surfaces 3a and 3a are provided opposite each other at the tip parts of the movable ring 3 and fixation ring 4, a pressure member 6 is provided at the outer periphery of the tip part of the fixation ring 4, and a spherical body 5 is pushed downward by an elastic member 7 provided to the pressure member 6. When the movable ring 3 is moved down, the spherical body 5 pushes the outer peripheral surface of the lens 2 along the conic surface 4a to align the lens 2.