"The rupiah strengthened due to the weakening of the US dollar and the shortfall in global crude prices," money market analyst Faisyal of Monex Investindo Futures said on Friday.
The rupiah traded at Rp13,973 per dollar earlier.
The Indonesian currency strengthened against the dollar also owing to a surplus in the country`s balance of payment in the fourth quarter of 2018, which strengthened the resilience of the external sector, he said.
After suffering a deficit in the previous quarter, the balance of payment saw a surplus of U$5.4 billion in the fourth quarter of 2018, fueled by a surplus in capital and financial accounts.
With the development, the country`s foreign exchange reserves at the end of December 2018 rose to $120.7 billion.
The rupiah opened lower at Rp13,975 per dollar in the morning trading. Throughout Friday, the rupiah moved in a range of Rp13,954 to Rp13,998 per dollar.
According to Bank Indonesia`s mid rate on Friday, the rupiah weakened to Rp13,992 per dollar compared to the previous close of Rp13,978 per dollar.
Reporting by Citro Atmoko, Suharto
Editing by Eliswan Azly