Fastfood restaurant is one of the fastest growing businesses in Korea. There has been a lack of research, however, fastfood restaurant operators should require affluent information of their consumers. The purpose of this study is, first, to examine the relationship between consumers’ involvement and demographic information, second, to investigate the relationship between consumers’ involvement and membership card usage, third, to examine the influence of involvement on consumers’ satisfaction, forth, to investigate the influence of consumers’ satisfactions on brand preference of fastfood restaurant. A survey has been conducted on 218 consumers of “L” fastfood restaurants in Busan. The results showed that a significant relationship between involvement, age and job, and also a significant difference in involvement by membership card usage. Additionally, the results show that consumers' involvement affected satisfaction, and satisfaction influenced brand preference. This study provides the practical marketing strategies for fastfood restaurant operators.