Moss balls of Lake Kutcharo were first reported by Ochi in 1956 from the beach near Kawayu and Nibushi. These moss balls were mainly composed of Drepanocladus fluitans var. kutcharokensis Kanda (=Leptodictyum riparium f. serieeum Nog. et Saito, nom. nud.) (Fig. 1, B). Moss balls have now been found at beaches of five places on the east coast of Lake Kutcharo (Fig. 2). Moss balls recently found at two places are mainly composed of D. fluitans var. kutcharokensis and Jungermannia exsertifolia Steph. (Fig. 1, A). At one site (Wakoto) the authors found abundant colonies of J. exsertifolia on concrete and boulders in the bottom of lake. One of the authors (Takita) found D. fluitans var. kutcharokensis and J. exsertifolia on the boulders in the bottom at Nibushi. It is interesting to note that moss balls were found at the places where hot springs are present on or near the beach.