The purpose of this paper is to clarify how Sawayanagi formed his view on women's higher education, which enabled the admittance of women to Tohoku Imperial University. We analyzed Sawayanagi's complete works compiled in ten volumes as well as his writings on women's higher education. The results are as follows : 1) Sawayanagi was convinced that women needed higher education just as men did, and made Tohoku Imperial University accept women in 1913. 2) Sawayanagi insisted that ability should not be determined by gender difference, and that those eligible should be offered equal opportunity of education. 3) Based on his experience, Sawayanagi advocated that equal opportunity of education should not be limited by the ascribed conditions such as economic condition, gender, social standing, and family lineage. Sawayanagi's belief and principles eventually led to the admittance of women to Tohoku Imperial University.