The incident, which took place on August four, came to light when the girl's mother lodged an FIR at Kotwali Women's police station today.
The 13-year-old girl, a student of local Tarak Das High School, was raped by Kala Chand Mondal while she was going to an agricultural field near her residence on the very day, they said.
A student of class VII, the girl had initially suppressed the matter out of fear, but narrated her ordeal to her grandmother yesterday.