In 2015, the population of people over the age of 65 is 25.0% in Japan. This means that Japan has already
become a super-aging society. In such society, the number of elderly people living alone has been also
increased. For such people, a fall accident is serious because it can lead to serious injury or death. Researches
and services to monitor behaviours of such people have been proposed. For example, by monitoring the status
of use of home appliances, something unusual happened to them can be predicted. However, such systems
cannot recognize the detailed behaviours like fall. Surveillance cameras have been introduced only outside the
house because of the privacy issues