Using event-related potential (P300 and CNV), the cognitive function of elderly subjects was compared with that of young subjects. It was found that the prolonged cognitive information processing induced by aging was reflected in the P300 and N400 latency. The effects of aging were not observed in the P300 amplitude. The CNV measurements, in the range of this study, did not reflect the effects of aging. This might be because the CNV reflects a higher cognitive function as compared with P300 and the effects of aging do not appear in such a function. The data also suggested that the cognitive style must be taken into account when evaluating the deterioration of cognitive functions with aging.