The purpose of this study is to explore the applicability of QFD to product development of clothes by empirically applying it to development of a specific clothes, middle and elderly women’s formal knitwear. The voices of customers(VOCs) for formal knitwear was collected through in-depth interviews with 25 customers, shop masters, and designers. Also, questionnaires of which respondents were 230 customers were used to rank the importance of the items of VOC. A QFD team of 10 knitwear experts implemented the task of translating VOCs into design attributes and measuring the values of the relationships between VOCs and design attributes. Importance ranking of the items of design attributes was obtained based on Lyman’s method. The results of this study were as follows. First, the customer requirements for formal knitwear were classified into five dimensions, that is, symbolism, aesthetic, fitness, usefulness, and maintenance. Second, the descending order of the necessity of improving the quality was maintenance, aesthetic, fitness, usefulness, and symbolism. Third, three-staged design attributes were obtained as a result of translating of VOCs into design attributes. Lastly, the descending order of the importance of design attributes was “sorts of yarn”, “sorts of color jacquard”, “color”, “tone”, “ease”, etc.