"Anybody can have a girlfriend...there is no evidence of any wrongdoing against my son", he told reporters when asked about the incident involving his son and the BJP attacking him on the matter.
"CCTV footage of the hotel does not show any wrongdoing," he said emerging from a seminar on water management.
Asked that BJP has made it an issue against him, Manjhi accused the opposition of hatching a "political conspiracy" against a CM who hails from Mahadalit, poorest among dalits, community.
Senior BJP leader Sushil Kumar Modi said in a Facebook post that the CM was defending his son in the case by not getting an FIR registered in the incident.
Kumar, also former deputy Chief Minister, used the issue to attack former Chief Minister Nitish Kumar and said "while all these things are happening in JD(U) rule he is watching trailer of 'Jungle Raj II' silently."
Taking potshots at Kumar, BJP has been describing JD(U) joining hands with RJD as return of bad days of RJD rule and has given it the name of "Jungle Raj II".
According to reports from Gaya, the CM's son accompanied by a lady policewoman of Bihar Military Police (BMP) allegedly flouted his father's position and asked a hotel to give a deluxe suite to them on Thursday.
Fed up with meeting such a demand from the CM's son, the hotel employees in Gaya locked the two inside the suite that day and raised an alarm. The boy managed to be released after coughing up cash, the reports said.