After Islamic revolution of 1979, the left wing had a new sphere to act in political eras, and overcastted on the other groups, but as soon as possible, the unreligious left leaved the political scene of Iran after revolution. It seems the religious groups –as the only legal political actors- are integrated under “Islamic Republic Party” but so soon, we saw the distinction between them all. Just after ending the 8 years war with Iraq -10 years after revolution- on 1989 the distinction between tow groups legitimized. “Clerical Society” announced the divergence from “Clerical Association”. This divergence was the first show of establishing tow rival party-groups in I.R. Iran which continued till now. This article is about the junction and studies the birth of one the tow political wing of Iran after revolution, what has called “left wing” in front of “right wing”.