In these days, various foot problems have been rapidly increasing. Hallux valgus(HV), one of the most popular foot diseases, is found especially in mid-aged women. The most common cause of HV is to wear with small and pointed shoes for a long time. If HV is left untreated, the deformity in the other regions of the foot also follows. Even though many motion analyses and radiologic studies have been applied to various foot diseases, they do not provide quantitative information on the detailed motion of the foot. The purpose of this study is to analyze detailed foot motions of the normal and HV patients using a multi-segment foot model. Ten healthy adults, who have no disorders in the lower extremity, participated in three dimensional gait analysis. Twelve HV patients of Grade 2 were also chosen for the study. Results showed that HV patients exhibited relatively smaller flexion/extension, especially in terminal stance. An early abduction at the ankle during terminal stance was also noted in HV patients, which resulted in an excessive abduction in subtalar joint. In HV patients, medial MP joints exhibited excessive amount of adduction during terminal stance. In HV patients, hallux MP joint and talocrural joint exhibited excessive external rotation over the whole period of gait cycle. Understanding the detailed foot motions by the present multi-segment foot model would be very useful to diagnose and to treat patients with various foot diseases, and helpful for the design of foot orthoses.