This research aimed at the appearance design of portable stereo considering Consumers' expected product images and applying their relationship with product's form constituting elements to build up several design principles. By questionnaire investigation and market survey, portable stereo's design and appearance characteristics were collected. Semantic differential technique was used to analyze and classify the design images into three major principles: beauty, quality, and practice. Based on Quantification I methodology, beauty and quality were identified as the highest and second highest priorities, respectively. Two prototype portable stereo designs were developed according to these two principles along with the authors' design idea.