A creation adapted from one or more pre-existing works is a derivative work and shall be protected as an independent work. This study examines the questions of derivative works. Taking the definition of the derivative work as a starting point, it discusses the relationship between the pre-existing work copyright and the derivative work copyright. This article also discusses whether it could apply the fair use doctrine to infringing derivative works. Finally, it discusses how to seek legal protection as the derivative work has been infringed.