The 21-year-old from Mendi, Southern Highlands Province, was arrested last week. He was charged with two counts of sexual penetration.
It is alleged he sexually assaulted a 14 year-old girl on two occasions between April and May 2017.
Manus Provincial Police Commander, Chief Inspector David Yapu, told Loop PNG he was caught red-handed on the second alleged occasion by families of the victim.
A complaint placed at the police station led to his arrest.
The man is currently in police custody and is expected in court next Monday.