We assessed the original and recent distribution of sea otters (Enhydra lutris) along the coast of Hokkaido, Japan, based on information of remains from archeological sites, old hunting records, and records of recent sightings obtained from interviews. Some remains, including pups from one archeological site, suggested the possibility that some small aggregations had historically been distributed around Hokkaido. However, sea otters seem to have disappeared prior to commercial hunting in the 18th and 19th centuries, as no records could be found documenting the hunting of otters around Hokkaido during that period. Since 1973, intermittent sightings of otters have been made around Hokkaido, and since 1996, the sighting frequency has increased. Between 1962 and 2001, 119 sightings and six dead otters were recorded around Hokkaido. The source population of these otters is probably in the Habomai Islands of the southern Kurils. However, due to increasing anthropogenic habitat disturbance, it is unlikely that a stable habitat for sea otters can be established in the coastal waters of Hokkaido.