An accumulation-type image pickup device having first and second accumulation periods receives light relfected from an eye illuminated by a light beam from an illumination device. A memory for storing a signal from the image pickup device stores an image signal of the eye generated in one of the two accumulation periods of the image pickup device. The illumination device emits light in only one of the two accumulation periods. A differential signal generation circuit generates a differential signal between an image signal generated by the image pickup device during the first accumulation period and an image signal generated in the second accumulation period. The visual axis of the eye is determined on the basis of the signal from the differential signal generation circuit.
Visual axis detection method