The occurrence of a brackish water crab Ptychognathus barbatus from Kochi and Ehime Prefectures, southen Japan, are reported. A 8.8mm carapace width male from the Mashino River (32°47′19″N, 132°53′31″E) in Tosashimizu City represents the second record of this species from Kochi Prefecture. This species is recorded for the first time from Ehime Prefecture on the basis of a 10.1mm carapace width female from the Kunomura River (33°12′35″N, 132°33′24″E) in Uwajima City.