After examining 465 registrations of design for an electric 'kotatsu' from 1955 to 1996,the following results have been achieved; Many devices for electric heaters were registered for several years after 1955. Many of the wooden frame for a 'kotatsu' were shaped like square, but in the 1980's, more and more 'kotatsu's began to have rectangular frames, and had the same function as a traditional low table in Japan. Most of the registrations of devices such as collapsible legs or detachable legs had been finished before 198O. An electric 'kotatsu' has more frequently been used all through the year since 1975. Since that time an electric 'kotatsu' has remarkably established its position as a traditional low table in the living or dining room in Japan.