The ship is known to have left from Kolaka, Southeast Sulawesi, for South Sulawesi.
Police have dispatched patrol boats to look for the missing ship. It is believed that the ship went underwater 12 miles (19 kilometers) away from its destination, Detiknews website reports.
According to Kompas.com, 122 people were on board. Reuters reports of 100 people on board.
The reasons of the shipwreck are still unknown.