Based on the literature published between 1927 and 2010 and an examination of new material of the specimens collected from Japanese marine fishes, a checklist is compiled for the following 32 nominal species and some unidentified species of the copepod genus Caligus from Japanese fishes: Caligus aesopus, C. bonito, C. brevis, C. calotomi, C. cordiventris, C. coryphaenae, C. cybii, C. dasyaticus, ... [Show full abstract] C. epinepheli, C. fistulariae, C. fugu, C. glandifer, C. hoplognathi, C. lalandei, C. laticaudus, C. latigenitalis, C. longipedis, C. macarovi, C. mebachii, C. orientalis, C.oviceps, C. pagrosomi, C. pelamydis, C. polycanthi, C. productus, C. punctatus, C. quadratus, C. sclerotinosus, C. seriolae, C. spinosus, C. tanago, C. triangularis, and Caligus spp. Information on C. undulatus reported in plankton is also included. This checklist contains information for each Caligus species regarding its host(s), attachment site(s), known geographical distribution in Japanese waters, and references. The new material consisted of: Caligus fistulariae from two fistulariid fishes, Fistularia petimba and F. commersonii (new host); Caligus fugu from two tetraodontid fishes, Takifugu poecilonatus (new host) and Lagocephalus wheeleri (new host); Caligus polycanthi from one monacanthid fish, Aluterus scriptus (new host); and Caligus punctatus from one tetraodontid fish, Takifugu niphobles (new host). Twenty-three, 17, 10, 5, and 2 nominal species of Caligus have been found, respectively, in the North Pacific Ocean, Seto Inland Sea, East China Sea, Sea of Japan, and Sea of Okhotsk.