Construction began in 1972 and the majority of the line was expected to open in 1975. However, the Teito Rapid Transit Authority did not have enough funds to build the line, which delayed its construction. On August 1, 1978, the first section of the Hanzōmon Line finally opened from Shibuya to Aoyama-itchōme, including through services with the Den-en-toshi Line. It was then extended to Nagatachō Station in September 1979.
