Fuchigami Reiko has become the first woman to be elected as president of the Japan Federation of Bar Associations.
She will assume the role for two years starting in April.
None of Japan's three judicial bodies of lawyers, prosecutors and judges have been headed by a woman.
Fuchigami, 69, was born in the southwestern prefecture of Nagasaki. She became a lawyer in 1983, and has served as president of the Tokyo Bar Association.
Speaking on Friday, Fuchigami said she will do her utmost to embody gender equality and help generate more respect for diversity.
Fuchigami says she strongly expects a part of the Civil Code stipulating that married couples in Japan must have the same surname will eventually be ruled as unconstitutional.
In most marriages in Japan, women have been changing their surnames to those of their husbands.