The function of product design has been an important part for success on new product development. We deeply studied 'Chocolate-Phone' case which is considered as a representative of adopting design-oriented new product development strategy. According to this study, we found three contextual factors and nine key success factors for design-oriented new product development. The contextual factors consist of the strong needs for innovative product development, customer's needs for the emotional value, competitive situation for the new product launching. The key success factors consist of design, development, marketing, overall sides. The key success factors of design side are to select talented designers and take an insight for market and communication skill. The key success factors of development side are to possess high technological abilities, to do divergence with removing or giving up some function, management's strong support. The key success factors of marketing side are to bring core marketers from outside, capacity to gather ideas from outside. The key success factors of overall side are to share design-oriented principle with other functions and to change member's mind from engineer-oriented to market-oriented.