The accused, Rajashekharan, a railway employee and son-in-law of the victim, was arrested last night, Hubli-Dharwad Police Commissioner BA Padmanayan told PTI.
He has been remanded to police custody.
"The accused has confessed to the crime but revealed that there were no other men involved in the crime," the police commissioner said.
However, the victim, in her complaint, had alleged that a group of four to five masked men had barged into her quarters and sexually assaulted her.
The victim, a peon at the Hubli Division of the South-Western Railway, had alleged that one of the men had taken away the gold chain.