While Japan at the end of the Edo period revised their national seclusion system and started to set forward with internationally opening policy, it was the training of translators to communicate at practical negotiations with foreign countries that was most urgently required. In the case of To tsuji 唐通事, Chinese translators at Nagasaki during the Edo period, some of the youths transferred themselves to be in charge of two languages, from solo translation for Chinese to translation for both Chinese and English. They later became very active in the frontlines for diplomacy, education and translation because of their English abilities during the periods from the end of the Edo to Meiji era. One of the typical examples was Ga Noriyuki. Ga Noriyuki was the person who flourished as a liege of Tokugawa Shogunate, a bureaucrat, an educator as well as a translator, who had been working as a Chinese translator at Nagasaki. It was his mastering English which brought him a great turning point for his life. This paper examines historical backgrouds and progress for Ga Noriyuki's mastering English from the view point of the alteration of To tsuji at Nagasaki during the periods from the end of the Edo to Meiji era, through full survey on articles on his carrers.