Takashima studied at the Han school Zōshikan.
Takashima fought in the Boshin War to overthrow the Tokugawa shogunate. He was commissioned into the fledgling Imperial Japanese Army in 1874. He served as vice-chief of the First Bureau of the Ministry of War, and Commandant of the Kyododan (School for Non-commissioned Officers).
During the Satsuma Rebellion, he fought against his former Satsuma colleagues, and led the IJA 1st Detached Infantry Brigade. Takashima was promoted to lieutenant general in 1883.
In 1884, Takashima was ennobled with the title of viscount (shishaku) under the kazoku peerage system, and in 1887 was awarded the Order of the Rising Sun 1st class.
In 1888, Takashima was commander of the IJA 4th Division. He became Minister of War in the first cabinet of Prime Minister Matsukata Masayoshi in 1891. Takashima was appointed to the Privy Council in 1892. In 1895, he became Vice Governor-General of Taiwan. He again took up the post of Minister of War under the 2nd cabinet of Prime Minister Itō Hirobumi and 2nd cabinet of Prime Minister Matsukata from 1896 to 1898, and was appointed again to the Privy Council from 1899 to his death in 1916.