Professor Takashi Oka was born in Tochigi Prefecture on January 21, 1950.
After graduating from the Hokkaido University School of Law in 1972, Professor Oka received his Masters of Laws degree from Hitotsubashi University Graduate School of Law in 1974.
Professor Oka was appointed as an assistant professor at the Hosei University Faculty of Law in April 1977 and became a professor at the faculty in April 1986.
Subsequently, he became a professor at the Gakushuin University Faculty of Law. He has been at the university since 2000.
Professor Oka has also served as the Director of the Institute for the Research Institutes for Oriental Cultures, Gakushuin University for nine and a half years since 2002.
In April 2017, he became the Head of the Department of Law at the University.