Diatom assemblage in the sediment of Lake Yamanaka was examined. A total of 221 taxa among 37 genera were recorded. All taxa, which occurred abundantly, were planktonic species, i. e. Aulacosira granulata, Cyclostephanos dubius, Asterionella formosa, Cyclotella radiosa, Tabellaria fenestrata, Fragilaria capucina. DAIpo value calculated with the relative frequencies of the taxon observed was 56.5.
