The U.S. Geological Survey reported the magnitude at 6.6. Japan rated it at 6.5, Taiwan News reported.
The earthquake, at a depth of about 5.5 miles, was centered about 27 miles south-southwest of Hualian, 39 miles southeast of Buli and 471 miles east-northeast of Hong Kong, USGS said.
Train services in the area were suspended for safety checks, officials said.
Officials said telephone service was interrupted.
The Taiwan News said a power outage in Shoufeng reportedly trapped people on a building's third floor.
Central Weather Bureau officials said it was the third inland earthquake of magnitude 6 or higher this year.