Anthony Kennard, 38, of Dover, was arrested on charges of unlawful sexual contact.
Investigators say the girls, a seven-year-old and a 10-year-old, were being watched by Kennard on December 31st when he allegedly held the girls on the floor.
Police say Kennard then reached under the 7-year-old's shirt to rub her back.
Investigators say the girls repeatedly asked to be let free.
Kennard let the 7-year-old girl up, investigators said, but shoved the 10-year-old on a bed and began rubbing her buttocks while holding her down.
Kennard has been sent to jail on $5,000 secured bond.