The Japanese Wood Pigeon, Columba janthina, is an endemic species that lives only on the East Asia-Pacific islands. The population of this species on Ulleung Island, South Korea varies in size with season, but the cause for this was unknown. We hypothesized that Japanese Wood Pigeons migrate seasonally between breeding and non-breeding sites and accordingly studied their movement from 28 June 2017 to 20 April 2018 using GPS transmitters. We report the first evidence of seasonal migration of Japanese Wood Pigeons to non-breeding sites (Okinoshima and Nishinoshima Islands in Japan), 278 km from the breeding site (Ulleung Island). This migration route was on the East Asian-Australasian flyway and constitutes the longest flight ever recorded for Japanese Wood Pigeons. Our finding has significant implications for understanding previously disputed aspects of the ecology of Japanese Wood Pigeons, including geographical isolation, hybridization, population retention, and patterns of movement.