An attempt was made to elucidate whether any psychrophilic bacteria inhabited on the Hokkaido coast in winter, and consequently an obligately psychrophilic strain of bacteria was isolated from sea water several meters off shore in the suburbs of Abashiri city in Hokkaido. This strain resembled Vibrio marinus in many morphological and physiological properties. Optimum and maximum temperatures for growth were about 15° and below 25°, respectively. This psychrophile was also halophilic and required about 0.4M NaCl for the maximum growth. Furthermore, morphological change was observed in the cultures at 10°, 15°, and 20°, particularly in the young stage at 20°.