We investigated the effects of γ-aminobutyric acid（GABA）on the stress, sleep, and urination of elderly people. Thirty-eight elderly people were given chocolates with 100 mg of GABA or placebo chocolates for four weeks. Salivary cortisol levels were measured as a stress indicator and a questionnaire survey about sleep and quality of life（QOL）was conducted. The GABA group showed only a small rise of cortisol level after 2 and 4 weeks, on the contrary, the placebo group showed significant increase of cortisol. The questionnaire survey showed that there was an improvement in the quality of sleep from the point of view of onset and maintenance of sleep, drowsiness in the morning, and recovering from fatigue in the GABA group after 4 weeks. Furthermore, the frequency of night urination significantly decreased in the GABA group. From the observation, we confirmed that GABA has an effect of easing stress, improving quality of sleep, and decreasing frequency of night urination.