Taiwan's Central Weather Administration (CWA) put the magnitude of the quake, which hit just after 5 pm (0900 GMT), at 5.7.
According to the USGS, it hit at a shallow depth of 11 kilometres (7 miles) in the sea about 44 kilometres (27 miles) southeast of Yilan county.
"The building was swaying," an AFP reporter in the capital said.
The CWA also issued mobile phone alerts warning people to "keep calm and seek cover nearby".
By around 5:30 pm, Taiwan's National Fire Agency issued a statement saying there was "no report of major damages".
Taiwan experiences frequent earthquakes due to its location between two tectonic plates.
The last major one occurred in early April, when the island was hit by a deadly 7.4 magnitude quake, which officials said was the strongest in 25 years.
At least 17 people were killed in the April quake, which triggered landslides and severely damaged buildings around the epicentre in the eastern city of Hualien.
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