Sasebo Naval Arsenal (佐世保海軍工廠 Sasebo kaigun kōshō?) was one of four principal naval shipyards owned and operated by the Imperial Japanese Navy.
The Sasebo Naval District was established at Sasebo, Nagasaki in 1886, as the third of the naval districts responsible for the defense of the Japanese home islands. After the establishment of the navy base, a ship repair facility was established in 1889 with a dry dock. With the addition of equipment and facilities for ship production by 1897, the "Sasebo Shipyards" were officially established, and renamed the "Sasebo Naval Arsenal" in 1903. Construction of the arsenal was supervised by the French engineer Louis-Émile Bertin.
In 1913, a 250-ton crane was installed, and the shipbuilding facilities expanded to permit the construction of large warships. With the mothballing of the Maizuru Naval Arsenal due to restrictions by the Washington Naval Treaty, much of the design and prototype work for new classes of destroyers and torpedo boats formerly done at Maizuru was shifted to Sasebo. The facilities at Sasebo were also used for the conversion of the Akagi and Kaga from battleships to aircraft carriers.