An ophthalmologic apparatus comprising: an optical system that includes an optical scanner , deflects light (LO) from a light source using the optical scanner , projects the light (LO) onto a subject's eye (E), and receives light based on returning light from the subject's eye (E); a movement mechanism that moves the subject's eye (E) and the optical system relative to each other; an image acquisition unit that acquires an image of the subject's eye (E); an abnormality detector that detects abnormality based on a reference image and the image of the subject's eye (E) acquired by the image acquisition unit ; a scan controller that controls the optical scanner to re-perform a first scan or a second scan so as to project light (LO) from the light source onto a start position of the first scan, which is being performed for the subject's eye (E) at an acquisition timing of the image of the subject's eye (E), or a start position of the second scan performed before the first scan, when the abnormality is detected by the abnormality detector ; and a tracking controller that controls the movement mechanism so that the optical system follows a movement of the subject's eye (E) based on the reference image and the image of the subject's eye (E), when the abnormality is not detected by the abnormality detector , wherein the abnormality is an occurrence of cause which inhibits the control of tracking, the image of the subject's eye is a fundus image of the subject's eye (E), characterised in that the abnormality detector detects the abnormality when a characteristic region is not detected based on luminance information of the reference image or the fundus image of the subject's eye (E). an optical system that includes an optical scanner , deflects light (LO) from a light source using the optical scanner , projects the light (LO) onto a subject's eye (E), and receives light based on returning light from the subject's eye (E); a movement mechanism that moves the subject's eye (E) and the optical system relative to each other; an image acquisition unit that acquires an image of the subject's eye (E); an abnormality detector that detects abnormality based on a reference image and the image of the subject's eye (E) acquired by the image acquisition unit ; a scan controller that controls the optical scanner to re-perform a first scan or a second scan so as to project light (LO) from the light source onto a start position of the first scan, which is being performed for the subject's eye (E) at an acquisition timing of the image of the subject's eye (E), or a start position of the second scan performed before the first scan, when the abnormality is detected by the abnormality detector ; and a tracking controller that controls the movement mechanism so that the optical system follows a movement of the subject's eye (E) based on the reference image and the image of the subject's eye (E), when the abnormality is not detected by the abnormality detector , wherein the abnormality is an occurrence of cause which inhibits the control of tracking, the image of the subject's eye is a fundus image of the subject's eye (E), characterised in that the abnormality detector detects the abnormality when a characteristic region is not detected based on luminance information of the reference image or the fundus image of the subject's eye (E). <EOS>