The incident happened under the jurisdiction of Taldangra Police Station when the girl had gone out to answer nature's call along with 10-year-old brother this morning, the police said.
The accused, a 19-year-old and resident of the same area, confessed to his crime during interrogation, Bankura SP Sukhendu Hira said.
The man strangulated the girl to death with her dupatta after raping her, the SP said adding, the girl's brother narrated the incident to the police.
The man has been arrested under various sections of the IPC and POCSO Act, he said.