According to BIS's monthly data, the country's nominal EER dropped 1.38 percent to 115.89 points in June compared with a month ago, hitting a seven-month low.
The real EER continued to decline for five consecutive months from 124.51 points in February to 120.42 points in June, BIS data showed.
The BIS EER indices cover 61 economies, including the United States, Australia, China and the Euro area countries.
The most recent weights are based on trade in the 2011 to 2013 period, with 2010 as the indices' base year.
Nominal EER is calculated as geometric weighted averages of bilateral exchange rates, while real EERs are the same weighted averages of bilateral exchange rates adjusted by relative consumer prices.