An ophthalmologic apparatus includes an irradiation unit irradiating a subject's eye with a measuring beam emitted by a scanning unit that performs scanning, a first acquisition unit acquiring a first image of the subject's eye based on the returned measuring beam from the subject's eye when the scanning unit performs scanning in a first sub scanning direction, a second acquisition unit acquiring a second image of the subject's eye based on the returned measuring beam travelling from the subject's eye, at timing different from that for the first image, while the scanning unit performs scanning in a second sub scanning direction opposite to the first sub scanning direction, and a calculation unit calculating blood flow velocity of the subject's eye based on a blood cell position in the first image, a blood cell position in the second image, and the sub scanning direction of the scanning unit.