Shiva Rawat, a class III student of Chaudhary Dwarika Prasad Academy at Rahilamau village in the district, was brutally beaten up by headmaster Lalit Kumar Verma on Tuesday, Superintendent of Police Abdul Hameed said.
The boy started vomiting after Verma punched in his stomach, police said.
When Shiva's condition deteriorated yesterday, efforts were made to admit him to a hospital but he died on the way, the SP said.
A case of culpable homicide has been registered and the headmaster arrested, he said.