Twitter user Atmay @hoveringfalcon said: "Modi and all ministers should wear such suits in regular office also. Kurta is outdated."
Another user, Rakesh Ranjan, @rakeshranjankr said: "He went inside plain in kurta dhoti (sic) and coming out in coat."
There were also several tweets wishing the prime minister best of luck for his meeting with Japanese Prime Minister Shinzo Abe later in the day.
Modi is visiting Japan on his first bilateral foreign visit outside South Asia. He is on a five-day trip to Japan.