By employing in-depth interviews with a total of 14 television producers, the study seeks to investigate how the use of documentary background music has changed in the rapidly evolving media technology. This study reveals two major findings. First, the use of traditional compositional background music in TV documentary has been decreased for the last 20 years, while library music with various sound sources has been more likely to be used due to its artistic value, its digitalized formats, and its convenience. Second, the popularity of the library music use has changed the cooperative relationship between TV documentary producers and music directors, and their views on background music. Overall, compared to the past, the new media technology (e.g., much easier, faster editing process and communication through e-mails) has helped to come up with the current trend of using more library music. This trend however implies that the dependency of library music only may lose the unique value of television documentary as a work of creative art and eventually downgrade the quality of the programs. Further practical implications are discussed.