Objective: The purpose of this study was to get the cognitive reaction time according to the intensity of auditory stimuli in older people and to differentiate the cognitive reaction time between older people and adults. Method: 49 subjects consisted of 32 older people and 17 adults. Cognitive reaction time was assessed with Simple Auditory Reaction of Foundation I in PSS CogReHab. Analysis of the data was done by using independent t-test. Results: The results were as follows: 1. There was a significant difference of the mean of cognitive reaction time to the intensity of auditory stimuli. 2. There was no significant difference from older people regardless of sexual distinction in mean of cognitive reaction time. However, there was a significant difference of the mean of cognitive reaction time in adults. 3. There was a significant difference between older people who got a job or not in 90 dB of auditory stimuli. 4. The mean of cognitive reaction time to the intensity of auditory stimuli in older people was slower than adults. There was a significant difference of the mean of cognitive reaction time between older people and adults in 70 dB of auditory stimuli. 5. The mean of cognitive reaction time to the intensity of auditory stimuli in older people did not have the significant difference in scholastic ability. Conclusions: The results of the study showed slowing of the cognitive reaction time in auditory stimuli to aging in older people. Therefore, applying silver industry and development of equipment for older people may maintain independent life.