Yoshioka Yayoi (吉岡 彌生, April 29, 1871 – May 22, 1959) was a Japanese physician, educator, and women's rights activist.

Yoshioka was born in what is now part of Kakegawa city, Shizuoka prefecture, where her father, a physician, advocated primary education for the village children.

Realizing the difficulty of this career path for women in Japan, she resolved to start her own school of medicine, which she did before she was 30 years old.

In 1938, the Japanese government appointed Yayoi and ten other female leaders to the "Emergency Council to Improve the Nation's Ways of Living," a pre-war mobilization effort.

Yayoi was depicted on an 80-yen Japanese commemorative postage stamp, on September 20, 2000 together with Naruse Jinzo and Tsuda Umeko.