He studied civil engineering and mining at University College London and returned to Japan in 1868.

After working for the government as a technical officer supervising the mining industry, he was appointed Director of the Railway Board in 1871.

[1] In 1891 Masaru Inoue founded Koiwai Farm with Yanosuke Iwasaki and Shin Onogi.

After retirement from the government, Inoue founded Kisha Seizo Kaisha, the first locomotive manufacturer in Japan, becoming its first president in 1896.

He died of an illness in London in 1910, during an official visit on behalf of the Ministry of Railways.