Krishna Kumar, who is a relative of Maharajpur MLA Satish Mahana’s driver, had made the hoax call in an attempt to extort money from the legislator.
He was arrested on Tuesday after his number was traced by police, SP (City) Shomen Verma said.
Mahana, who owns Saraswati Vidya Mandir school in Lal Bangla area, had told police he received a call on his mobile phone threatening to blow up the school on Monday morning.
A team of police officials accompanied by bomb squad and sniffer dogs evacuated the school premises and carried out a search.
However, no bomb was found at the school where 900 children from class VI to XII study.