A cognitive impairment diagnostic device (1) includes: an obtainer (41) that obtains a distribution map representing a distribution of gaze points of a subject on a movie for cognitive assessment; and a diagnoser (39). The movie for cognitive assessment includes, in time order: a first movie including a first region including an image for encoding displayed in a visually enhanced manner, and a plurality of second regions including normal images displayed without being enhanced; and an assessment movie including a third region including an assessment image similar to the image for encoding and displayed at a same position as the image for encoding without being visually enhanced, and the second regions. The diagnoser (39) calculates, in a distribution map on the assessment movie, a percentage of fixation duration for which the third region is focused on, and makes diagnosis of suspected memory impairment when the percentage of fixation duration is lower than a threshold.
