A wavefront aberration compensating apparatus includes: a deformable mirror which compensates a wavefront aberration of a light flux entered, the deformable mirror including a plurality of electrodes, and a thin-film mirror which changes a configuration thereof in accordance with a voltage value applied to each of the electrodes an optical system provided with the deformable mirror, and including an object subjected to aberration compensation a wavefront sensor which receives the light flux traveled through the object and the deformable mirror, and which measures the wavefront aberration of the light flux and a controller configured to calculate the voltage value applied to each of the electrodes, on the basis of differences, from a signal outputted from the wavefront sensor, between application points on the thin-film mirror and target points both corresponding to the electrodes, respectively, and to repeat compensation of the configuration of the thin-film mirror of the deformable mirror on the basis of the calculated voltage value, such that the wavefront aberration of the light flux measured by the wavefront sensor is suppressed.
