The second Nagato-class battleship MUTSU Sank by internal explosion of uncertain cause, at Hashirajima anchorage past 12pm on 8 June 1943. After WWII, MUTSU was salvaged. 30 percent of the hull remains in the Seto Inland Sea. We made a survey of MUTSU with a Under Water Drone at a the depth of 15～40 meters. This spot is 4.5 kilometers away from the MUTSU Memorial Museum.