Former Construction Minister Shozo Harada collapsed after suffering a stroke Monday during a gathering in Shimada, Shizuoka Prefecture.
He was rushed to a nearby hospital, where he immediately underwent surgery, officials at his office said.
Harada, 79, a Liberal Democratic Party member in the House of Representatives, collapsed at around 3:10 p.m. He was later moved to the hospital's intensive care unit, according to the officials.
Harada represents the Shizuoka No. 2 district and is serving his ninth term in the Lower House. He has been chairman of the Lower House Budget Committee and was construction minister in the Cabinet of Prime Minister Toshiki Kaifu between 1989 and 1990.
He is currently chief of the LDP political reform headquarters and chairman of the LDP Shizuoka Prefectural Chapter.