Reminiscence is a non-pharmacological intervention that involves a narrative and reflective process of recalling past thoughts, feelings, and experiences. The positive effects of reminiscence intervention for cognitively intact older people have been reported ; however, the physiological mechanisms underlying the effect on the frontal lobe during and after the reminiscence are not well understood. We have demonstrated increased oxygenated hemoglobin concentrations in the right frontal lobe and decreased deoxygenated hemoglobin concentrations in both the frontal lobes during reminiscence in cognitively intact older participants using near-infrared spectroscopy. Furthermore, the mood state of older participants was evaluated using Profile of Mood States and increased subjective health perception scores and showed a significant improvement following reminiscence compared with pre-reminiscence. Reminiscence-based intervention activated the frontal lobe and provoked positive emotion in the mood state and health perception in cognitively intact older participants. These findings may improve treatment strategies of older adults for better quality of life.