A 57-year old male, who had taken part in a field investigation of Japanese serow, Capricornis crispus, was bitten by a tick in Shimokita Peninsula in Aomori Prefecture, northern Honshu, Japan in late December 2007. The female tick was found attached to his left chest. The author, who also took part in the field investigation, removed the tick with forceps. Examination of the tick revealed that it was Ixodes acutitarsus (Acari: Ixodidae). As the mean temperature on the day that he was bitten was 3.7°C, this suggests that I. acutitarsus is active at around 0°C.