This would be the fifth time that Mr Kumar would take oath as Bihar Chief Minister.
Bihar Chief Minister Nitish Kumar today called Shiv Sena president Uddhav Thackeray and invited him for his oath-taking ceremony to be held in Patna on November 20.
The Sena chief, however, expressed his inability to attend the ceremony, but told Mr Kumar that two senior party leaders would remain present.
"Nitish Kumar called me and lovingly invited me for his oath taking ceremony on November 20. I told him that I will not be able to attend the ceremony, but senior Sena leaders, including Subhash Desai and Ramdas Kadam will definitely attend the ceremony," Thackeray told reporters at his residence "Matoshree" in Mumbai.
A source close to Thackeray said both the leaders have planned to meet next month.
This would be the fifth time that Mr Kumar would take oath as Bihar Chief Minister.
The grand alliance comprising the RJD, JD(U) and Congress won the Bihar elections. The RJD emerged as the single largest party with 80 assembly seats, followed by the JD-U (71) and Congress (27).