A new dragonet, Foetorepus masudai, is described from southern Japan. This is the species that Nakabo (1983) mistakenly identified as Foetorepus delandi. It is characterized by large eye, filamentous 1st dorsal spine in adult males, 1st dorsal fin without an obvious dark mark, a dark spot on upper origin of pectoral fin and a large dark blotch on posterior half of pelvic fin. A revised key to the species of Foetorepus found in Japan is included.
