A Sundanese artist M.A. Salmoen wrote in his book of 1942 that the beginning of radio broadcasting in 1935 marked the division between so-called the "classic" and the "modern" in Sundanese music. This paper is intended to explore the development in Sundanese music broadcast by radio between the 1930's and the 1950's and to consider what characterized the "modern" era in Sundanese music. Since the middle of 1930's, Sundanese musicians had attempted to innovate their music in many aspects, for example, improving musical instruments, developing new playing technique for them, combining Western instruments to Sundanese ensembles, and so on. Most of these efforts seemed to be related to the development of a type of song called kawih, which is now usually understood as a metricized song with some exceptions. While kawih has existed for a long time, many musicians had competed to compose new repertoire of kawih. Simultaneously, female singers who sang that repertoire enjoyed great popularity through radio broadcasting. Radio introduced a new way of musical communication that could not be imagined before and was one of the most influential factors for musical change. I will argue that radio was a main source of imagination of the "modern" in Sundanese music.