Automatic Identification System (AIS) equipment has been fitted to all vessels above 500 gross tonnage and to those 300 gross tonnage that are trading internationally. Information concerning the vessel's navigational data, such as position, heading and speed together with other relevant information such as ship's name, dimensions and destination, are automatically transmitted to other vessels and to facilities. Kanmon channel is one of the most congested passages and there is strong tidal current. We received and saved AIS data around Kanmon Channel by MS receiver and analyzed the traffic characteristics, such as number of vessels, relation between tidal current and vessels' length, and destination.