Indonesia's military has a record
of human rights abuse in Aceh
Military officials said the private soldiers were being held at military police headquarters in the war-torn province.
The rapes took place separately from 20 to 22 June. The troops could face up to 12 years in jail if found guilty at a later hearing.
It was the second time rapes had been reported since the military and police launched an assault on Aceh in May to crush Free Aceh Movement separatists, who have been fighting for independence since 1976.
Earlier in June, a police paramilitary soldier was detained for allegedly raping a 15-year-old in the mainly Muslim province.
The military, which has a record of gross rights abuses during earlier campaigns in Aceh, has said it will try to ensure its troops behave better this time.
Six soldiers were jailed for four to five months for beating up civilians during the campaign.
Foreign media and overseas non-government organizations have been restricted to travel in Aceh by martial law authorities, making independent monitoring of rights abuses difficult.