The present invention is intended to provide an adaptive optics system and an optical device that allow correction of wavefront phase aberration with higher accuracy than before and have a wider correction range than the conventional ones, regardless of the distance between the observation target and the fluctuation layer, and the size of the observation target. An adaptive optics system includes: a wavefront phase modulator that makes aberration correction to incident light and emits the corrected light; and an imaging-conjugated position adjustment mechanism that adjusts freely within a specimen the position of a surface imaging-conjugated with a fluctuation correction surface formed by the wavefront phase modulator. The imaging-conjugated position adjustment mechanism adjusts the fluctuation correction surface to be imaging-conjugated with a fluctuation layer existing in the specimen.