PROBLEM TO BE SOLVED: To improve the detection accuracy.SOLUTION: A detection apparatus includes: a display； an imager for taking an image of a subject； a sight line detector for detecting the direction of a line of sight of the subject from the taken image taken by the imager； an output controller for controlling the display to display a diagnostic image including a person image and a geometric pattern image； and a sight point detector for detecting a first sight point that is a point of sight of the subject in the person image, and detecting a second sight point that is a point of sight of the subject in an area of the geometric pattern image, on the basis of the direction of the line of sight, the area including at least one of the center of geometric patterns, a characteristic part of the geometric patterns, a part containing denser lines forming the geometric patterns than the other parts, and a part containing a change in the geometric patterns.
