This could be because of a "deal" between the Bharatiya Janata Party (BJP) and the Congress, the Aam Aadmi Party leader said in a statement on video.
Kejriwal's comments came a day after Congress Vice President Rahul Gandhi alleged that Modi took bribes from corporate houses when he was the Gujarat Chief Minister.
Gandhi, who echoed what Kejriwal said more than a month ago, said the corruption allegations against Modi came to light following an Income Tax department raid on the corporate houses in 2013.
A Congress-led coalition ruled India from 2004 to 2014, when Modi became the Prime Minister.
"When Modiji's name figured in the papers of Birla during the IT raid, that time he was just a PM candidate of the BJP. The Congress had its own government at the Centre. Then why they (Congress) did not raise this matter then?" Kejriwal asked.
"Was any deal struck between BJP and Congress at that time?"
Kejriwal, who has been making corruption allegations against the Prime Minister, on Wednesday sought a Supreme Court-monitored probe into charges that Modi was given bribes when he was the Gujarat Chief Minister.