The biopic, which will feature Ranbir Kapoor, will be helmed by Anurag Basu.
"I've written the Kishore Kumar biopic. I write films for friends. There are certain films you feel I want to direct when you write them. When I was writing Kishore Kumar's biopic, I felt the same and Anurag knows about it," Sen told IANS.
However, he is happy that he got a chance to write the movie at least.
"His (Anurag's) understanding is superior than mine. I don't think anyone else would have trusted me to write such a massive film. I understand there are certain commercial aspects as well," he added.
Meanwhile, Sen is busy promoting his debut directorial "Gulaab Gang", which stars Madhuri Dixit and Juhi Chawla.
He says he would not have directed the film if Madhuri was not on board.
"I would not have made this film if Madhuri had said no. Nobody would have put in money for a project where there are no saleable lead actors for a film by a debutant director. I did go around with the script and Madhuri agreed to it. If Madhuri was not in it, this film wouldn't have been made," said Sen.