PROBLEM TO BE SOLVED: To provide a head mounting type pupil detecting device, small-sized, used even in a mobile environment, and securing an external visual field.SOLUTION: This head mounting type pupil detecting device includes: a light receiving part (12) disposed in a position away from the front of the visual field and configured to receive the reflected light from an eyeball and generate an eyeball image an optical system (11) for guiding the eyeball image onto the light receiving part and a pupil detecting means (13, 14) for detecting a pupil from the eyeball image, wherein the visual field of the light receiving part to the eyeball is limited to be smaller than a movable range of the pupil depending on the movement of the eyeball at least in one direction.
