Despite being well-researched in several other bear species, the act of infanticide has yet to be documented in Asiatic black bears (Ursus thibetanus). We captured video footage of an apparent infanticide event in May 2016 using sensor cameras placed outside the winter den of a known female in Nagano Prefecture, Japan. We observed the presence of a known male outside the den, interacting with the female and her offspring. The female ultimately died and her body did not appear to have been consumed by the male bear. From our observations we considered both sexually selected infanticide and nutritional demand as possible motives behind the male's attack.