Police said the 45-year-old man was found hanging in the toilet of the correctional home (jail) in North Dinajpur district this morning.
He was arrested on July 29 on the charge of raping his 14-year-old daughter in their house when his wife had gone to her parent's house for a month.
The girl had told her mother on her return that she had been raped regularly by her father during the period of her absence.
A case was started against him under POSCO and the IPC. The man's bail prayer was rejected by the North Dinajpur chief judicial magistrate court and he was remanded to judicial custody for 14 days.