An ophthalmologic apparatus includes a data acquisition unit, a storage unit, and a correction unit. The data acquisition unit includes a concave mirror and an optical scanner configured to deflect light from a light source to guide to a reflective surface of the concave mirror. The data acquisition unit is configured to acquire a first data set group in an A-scan direction by performing optical coherence tomography on a subject's eye placed at a subject's eye position or a conjugate position of the subject's eye position using light reflected by the reflective surface. The storage unit is configured to store correction data for correcting an incident angle of the light at the subject's eye position depending on a deflection angle of the light by the optical scanner. The correction unit is configured to generate a second data set group by correcting at least a part of the first data set group based on the correction data stored in the storage unit.