Although the Internet has been widely used in Japan, the quality of information on mental health-related issues has not been evaluated so far. The purpose of the present study was to investigate the current status of Japanese websites that deal with mental health, mental disorders, and their associated matters. Using a search engine, Google, 37 websites were identified that exclusively contain information on mental health or mental disorders. The characteristics of the sites were then examined, along with variety of mental disorders mentioned, and quality of contents for each of the 37 websites. More than half of the websites were set up, at least in part, for commercial purposes and only 27% of sites were owned by professionals. Mood disorder, panic disorder, and schizophrenia were the three most commonly referred disorders on websites. Aside from some exceptions, the quality of information was inadequate, especially that regarding treatment. Most of the websites on mental health and mental disorders examined in the present study have scope for improvement. The challenge is to establish a system to evaluate the sites and to motivate each webmaster to improve the sites.