The girl's family and the accused were tenants in the same building, police said.
The accused used to play with the girl, who considered him "like her grandfather". So, the parents did not suspect anything when the accused took the girl to his house under the pretext of giving her sweets, police said.
Yesterday, the girl complained to her mother about pain in her private parts and her ordeal for a week. Her mother informed her husband who then called the police.
The accused was arrested last night from his residence.
The girl and her parents have started undergoing counselling sessions, police said.
The accused was living away from his family and was not employed anywhere, they added.