We investigated the relationship between daily physical activity level and response inhibition control aspect of cognitive function in older adults using event-related potentials. Twenty-eight Japanese older adults (70.6 ± 3.8 years) participated in the present study. Daily physical activity (PA) was measured using an accelerometer, including step count and the intensity of PA. Participants were divided on the basis of their step count into “Higher PA group” (more than 10,000 steps/day, n = 14) and “Lower PA group”(less than 10,000 steps/day, n = 14). Cognitive function was evaluated by performance, NoGo-N2, and NoGo-P3 while they performed a Go/NoGo task. The results indicated that the Higher PA group exhibited shorter reaction time on Go trials, relative to the Lower PA group. NoGo-P3 amplitude was larger in the Higher PA group compared to the Lower PA group, but NoGo-P3 latency did not differ between groups. PA was positively correlated with NoGo-P3 amplitude. NoGo-N2 component was not related to PA. Thus, PA was more sensitive to monitoring of the outcome of response inhibition rather than pre-motor inhibition in Go/NoGo task. These findings suggest that daily PA is associated with preservation of age-related declines in response inhibition control.