A male specimen of Argulus coregoni Thorell, 1864 was collected by a hand net in the Chimidani River, a tributary of the Yura River, in Miyama Town, Kyoto Prefecture, central Japan, on 16 September 2005. The specimen most likely detached from an unidentified fish (probably a fluvial amago salmon Oncorhynchus masou ishikawae) caught in the net. Specimens of Argulus japonicus Thiele, 1900 were collected from the body surface of a freshly dead common carp (Cyprinus carpio) in a rearing pond at Aquapia-Akutagawa in Takatsuki City, Osaka Prefecture, central Japan, on 26 August 2011. These collections represent the second records of A. coregoni and A. japonicus from Kyoto and Osaka prefectures, respectively.