Cho Sonjin (born April 18, 1970) is a professional Go player.
Cho was born in South Korea, but moved to Japan at age 12 in order to become a professional.
He accomplished his goal two years later in 1984.
He was promoted to 9 dan in 1998.
In 1999, he defeated Cho Chikun in the Honinbo, ending Chikun's 10-year run with the title.