A gaze detection apparatus comprising: a display screen on which an image is displayed; a light source configured to apply detection light to at least one of the eyeballs of a subject; an image data acquisition unit configured to acquire image data on the eyeball to which the detection light is applied; a position detector configured to detect, from the acquired image data, positional data of a pupil center representing a center of a pupil of the eyeball to which the detection light is applied and positional data of a corneal reflection center representing a center of corneal reflection; a point-of-regard detector configured to calculate, based on a position of the pupil center and a position of the corneal reflection center, positional data of a point of regard of the subject on a plane containing the display screen; and a controller configured to perform a calibration operation including displaying a target image in multiple positions on the display screen sequentially, setting, in the display screen, corresponding areas corresponding to the target images displayed on the display screen sequentially, and calculating positional data of the points of regard in display periods in which the respective target images are displayed; and determine, with respect to each of the target images, whether the positional data of the point of regard that is calculated in the calibration operation is present within the corresponding area; characterized in that the controller is further configured to: when the number of valid target images, that are the target images on each of which it is determined that the positional data of the point of regard is present within the corresponding area, is at or above a threshold, output the positional data of the points of regard of the valid target images as calibration data; and, when the number of the valid target images is under the threshold, cause the calibration operation to be repeated. a display screen on which an image is displayed; a light source configured to apply detection light to at least one of the eyeballs of a subject; an image data acquisition unit configured to acquire image data on the eyeball to which the detection light is applied; a position detector configured to detect, from the acquired image data, positional data of a pupil center representing a center of a pupil of the eyeball to which the detection light is applied and positional data of a corneal reflection center representing a center of corneal reflection; a point-of-regard detector configured to calculate, based on a position of the pupil center and a position of the corneal reflection center, positional data of a point of regard of the subject on a plane containing the display screen; and a controller configured to perform a calibration operation including displaying a target image in multiple positions on the display screen sequentially, setting, in the display screen, corresponding areas corresponding to the target images displayed on the display screen sequentially, and calculating positional data of the points of regard in display periods in which the respective target images are displayed; and determine, with respect to each of the target images, whether the positional data of the point of regard that is calculated in the calibration operation is present within the corresponding area; characterized in that the controller is further configured to: when the number of valid target images, that are the target images on each of which it is determined that the positional data of the point of regard is present within the corresponding area, is at or above a threshold, output the positional data of the points of regard of the valid target images as calibration data; and, when the number of the valid target images is under the threshold, cause the calibration operation to be repeated. when the number of valid target images, that are the target images on each of which it is determined that the positional data of the point of regard is present within the corresponding area, is at or above a threshold, output the positional data of the points of regard of the valid target images as calibration data; and, when the number of the valid target images is under the threshold, cause the calibration operation to be repeated.