Technically Correct. It's official name is not "Republic of Taiwan" it's "Republic of China", which officially consists of Mainland China, Hong Kong, Macau, and Taiwan.

Currently, Mainland China, Hong Kong, Macau, are under rebel occupation by the so-called "People's Liberation Army" commanded by the "Communist Party of China". Taiwan is the only remaining area under ROC control, along with the Kinmen Islands as part of the "Free Area of Republic of China".

Well, at least, that's the official view held by the Government in Taiwan, anyways. They never officially claimed to be "Republic of Taiwan", but are, nevertheless, a de facto country under the name of "Republic of China".