In order to search for juvenile Apostichopus japonicus, the attached organisms were detached from every 30 cm depth of two steel sheet piles in the framework of a jetty in 3 m depth of water in a shallow harbor area in Yoshimi Bay. A total of 103 species of benthic animals were observed attached to the whole surface of the two steel sheets, and the most numerous 48 species of them were observed in the section of 60-90 cm below the top of the sheet. The total amount of attached organisms was largest in this section, where the oyster Crassostrea gigas was dominant. Two juveniles of A. japonicus of the green colored type were separately collected from the section of 210-240 cm and 240-270 cm, where the bivalve Chama japonica was dominant. They were very hidden in the attached organisms and were considered to belong to 1-year age group settled on the sheet piles.