The Maoists used dynamites and cylinder bombs to blast the high school building at Narotampur, district police official Sanjay Singh said.
He said the two-storey building collapsed in the blast, but no casualty was reported.
The school was targeted as paramilitary personnel (CRPF) had camped there till mid-April for combing operations against Maoists in Lakhisarai and neighbouring districts.
More than 250 students will now not be able to attend school, and will either sit under tress or miss classes altogether.
"For Maoists, schools have become a soft target but it badly hits the children," the police officer said.
It is not the first school destroyed by the rebels.
The Maoists blasted a school building in Jamui district too last week.