Many past studies have shown the effects of music listening in many domains. This study aims to investigate the effects of listening to music related to design project on designer's idea generation. The within-subject design was adopted in the experiment. The subject carried out lamp design under listening to music related and unrelated to design project. After the experiment, they performed retrospective reports. The results indicated that listening to music related to the design project can create an atmosphere with the design theme and provide hints to the hearing resources, helping designers guide the direction of idea development. Moreover, while listening to music related to the design project, the majority of subjects can generate more ideas associated with the design theme as well as the episodic memories. Consequently, they tend to express their ideas by the things relevant to design project they usually contact. However, in the situation where music not related to the design project is playing, subjects generate fewer ideas related to the style of design project and they tend to develop their ideas based upon the design elements required for lamp design.