There have been many studies showing the effects of music listening in many domains, but research regarding the impact of music listening on design is rare. The experimental task adopted in this study uses the within-subject design method to investigate how music affects idea generating behavior. The subjects were invited to draw lamp sketches by freehand while music related or unrelated to the design theme was playing. The subjects’ retrospective reports, which they generated in the design process, were decoded and statistical methods were applied to compare the quantities of lamp sketches, as well as with previous relevant studies. The results show that, when listening to music related to the design theme, the subjects spent more time in drawing sketches and generated more lamp sketches than when listening to music unrelated to the design theme. In the case that music unrelated to the design theme was playing, the subjects spent a longer time in arbitrary graffiti and thinking. Writing text, however, was not significantly different under these two music situations. This study demonstrates that designers will have a more fluent idea manipulating procedure when music suited to the design theme is playing. We speculate that the reasons might be attributed to the attention theory of cognitive psychology as well as episodic memory which was induced by music fit to the design theme.