The present study investigated age-related changes in the time-varying hemodynamics of the prefrontal cortex by using near-infrared spectroscopy (NIRS). NIRS is a real-time spectroscopic method used to measure functional hemodynamic responses related to neural activation in the brain. The prefrontal hemodynamic responses of 17 young adults and 21 elderly adults were monitored while they completed the Wisconsin card sorting test (WCST). The results revealed a slower activation pattern in oxyhemoglobin concentrations in the elderly group than in the young group. Furthermore, quantified results revealed time- varying trends in hemodynamic responses. The findings imply that age-related decline in hemodynamic responses may contribute to poorer performance during cognitive tasks.