An adjuster for an optical pickup performs focus servo control of an objective lens (14) by a focus error signal generating circuit (84), a focus servo control circuit (85), and a drive circuit (86) by using a part of laser light entering in a Shack-Hartmann sensor (60). Alternatively, an adjuster for an optical pickup performs servo control in two directions, control in the X-axis direction, shown in the figure, of the objective lens (14) and control in the Y-axis direction, shown in the figure, of a collimating lens (41), the servo control in two directions being made by a position calculating circuit (94), an X-Y direction servo control circuit (95), and drive circuits (96, 97) by using a part of laser light entering in the Shack-Hartmann sensor (60). |