Schools and offices on the northern half of the island planned to close Friday as the storm, classed as a super typhoon but later downgraded to a medium-force typhoon, crept west-northwest at about 10 miles per hour.
Sustained winds of 100 miles per hour and more were already lashing the southernmost Ryukyu Islands of Japan Friday.
The Ministry of National Defense prepared military camps as emergency shelters, canceled flights and rail services and readied emergency response forces to react at a moment's notice, the Central Emergency Operation Center said.
It also issued landslide warnings for central Taiwan, where two recent earthquakes loosened soil that could easily turn deadly as Soulik dumps as much as two feet of rain over the mountainous spine of the island. Coastal areas were warned against a 6 to 10-foot storm surge.
Soulik was expected to arrive in China's eastern Fujian and Zhejiang provinces Saturday, although it will likely be weakened after crossing Taiwan's mountains.