To clarify the taxonomy and the distribution on subclass Aspidochirotacea and Apodacea, the authors examined the materials which were collected from 48 localities during the period from 1962 to 1995 . As a result, the specimens of holothurians are classified into 3 orders, 5 families and 8 specie. Among them , the following 4 species are found to be new to the Korean fauna : Molpaida oolitica, Paracaudina chilensis, Acaudina molpadioides and Caudina similis.