In 1960, the authors investigated the floating seaweeds around Japanese waters. Since the floating seaweeds in northern Kyushu were remarkable by their mass in May and June, as reported previously, the authors intensively made three surveys from March to August. Eight waters were chosen along the both sides of Japan. They are the regions around the Goto Islands, of the north of Tottori Prefecture, around the Noto Peninsula, and of the west of Akita Prefecture on Japan Sea coast, and around the Osumi Penisula, of the south of Kii Peninsula, around the Izu Peninsula, and of the east of Kinkazan on the Pacific coast. In Japan Sea side much were alike with the case of northern Kyushu with regard to the species found in floating seaweeds and their quantitative change with the season. But in northern regions gradual increase of S. confusum and gradual decrease of Eusargassum species were recognizable. In the Pacific side the results from each region differed considerably. Especially in the east of Kinkazan the species growing in northern Japan were collected in general, while in the other regions warm-water species were dominant.