Yadav died of cardiac arrest at Madhubani in Bihar late last night.
He is survived by his wife and and three sons.
Chief minister described Yadav at a fighting and committed social activist and leader and recalled his contribution for the uplift of the poor people of the society.
His death has caused an irreparable loss to politics and society, Kumar said and prayed god for giving strength to his family members and followers at this hour of sorrow.
RJD chief Lalu Prasad and Bihar Youth Congress Chief Lalan Kumar while condoling his death, recalled contributions of Yadav who was once MLA from Bisfi in Madhubani.
State Youth Congress activists also organised a condolence meeting.
"People of the state and Madhubani will continue to remember his contributions," Lalan Kumar said.