Sepia erostrata is a species of cuttlefish native to the northwestern Pacific Ocean, specifically off western mainland Japan, from Sagami Bay to the Kii Peninsula. It inhabits subtidal, inshore habitats. S. erostrata grows to a mantle length of 90 mm. The type specimen was collected off Manazuru, Kanagawa Prefecture, Japan. It is deposited at the University Museum of the University of Tokyo.