Making product differentiation in quality has been becoming difficult with progress of production technology, and aesthetic design is given increasing importance in the charm of products. Previously, appearance design was creation activity strongly depending on the aesthetic sense of a designer. Nowadays, it is demanded to survey consumer's needs on appearance design and reflect them on product design; in other words, design based on only designer's Kansei is not enough for customer's preference. It becomes important challenge to effectively gather consumer's needs, extract valuable information from the needs and apply them for product development. There are several works which create a shape in harmony with consumer's preference. However, they do not accept designer's intention in the design process. This study thus aims to construct a design support system which can provide design ideas (design solutions) to the designer at an early stage in the design process. The provided design ideas are generated from a designer's original idea by adding consumer's preference. A system to collect consumer's preference data using interactive genetic algorithm was constructed. The system can make if-then rules as consumer's preference based on rough sets theory and create design solutions by applying the consumer's preference rules on a designer's idea.