Art Deco, a style of luxury, opulence and modernity in the 20th century, was popular from 1909 to 1930s.The definition of Art Deco tends to be either over simplistic or bafflingly complex (Hillier &Escritt, 1997) because Art Deco covers such a wide range of design.Consequently, it creates some confusion in regard to the history of art, industrial design and fashion because this era was a transition period between handcraft-work and machine-work. Therefore, this study examines a complex definition of Art Deco by comparing the differences of Art Deco style that were shown in Chanel designs which reflected the suitable imagery of machine age and Paul Poiret designs which had both modern imagery and simplified traditional ornamental characteristics. Chanel designs have been regarded as a representative sample of modernism fashion(De La Haye & Tobin, 1994). However, Chanel applied the principles of Art Deco style as well as modernism because the golden age of Art Deco overlapped with modernism. Yet, Chanel designs have never been studied from the view point of Art Deco style. Meanwhile, Paul Poiret was well known as the first designer who translated the spirit of the modern times into revolutionary garments. His interest in the simplicity of traditional garments led him to establish the foundation of Art Deco fashion(Lussier, 2003). This study was conducted by a review of the literature. Theoretical studies about the historical background of Art Deco period, characteristics of Art Deco fashion and Poiret & Chanel design analysis were preceded. Art Deco was influenced by various factors such as Orientalism, Ballets Russes, Fauvism, Cubism, Futurism Constructivism, Purism, Bauhaus and De Stijl(Robinson & Ormiston, 2008). The characteristics of Art Decostyle can be summarized as simplified shapes &silhouettes, bold, strong& practical colours, motives and patterns of simplified forms of nature& geometric forms, various details& trimmings, and flashy& artificial jewelries(Cho & Park, 1991; Klein, McClelland, & Haslam, 1986; Lussier, 2003). In this study, the differences in Poiret and Chanel designs were examined by five elements; silhouette, colour, pattern & motif, decoration and jewelry. The results were as follows: 1. Differences in silhouette: narrow-long shapes with high waists and streamline silhouettes by hobble skirts were mostly shown in Poiret designs while straight box and tubular silhouettes with law waists were mostly used in Chanel designs. 2. Differences in colour: strong& rich colours, glittering metallic colours and sharp colour contrast were shown frequently in Poiret designs, while black and neutral colours such as brown, beige were often used in Chanel designs. Poiret’s clothings introduced a riot of bold colours into fashion and Chanel made the black as a popular working outfit colour. 3. Differences in pattern & motif: simplified motives and patterns adapted from nature were used more than geometric patterns in Poiret designs while geometric patterns made with various lines and shapes were mostly used in Chanel designs. 4. Differences in decoration: Poiret still used various details and trimmings such as decorating gems, furs, tassels, flounces, frill, drapes, beads and embroidery which made costumes luxurious and exclusive. However, Chanel tried not to use any decorations which are at risk for transforming straight silhouette to curvy silhouette, but she decorated surface of the clothing by tucks, pleats, beads, fringes, embroideries, frills, pockets and ribbons of various sizes. 5. Differences in jewelries: precious genuine jewelries and were used to make Poiret's garments look more gorgeous, while Chanel created artificial jewelry to decorate simple and straight clothing. The results of this study show that significant differences can be made by adapting different design elements under the same style. Both Chanel and Poiret applied principles of Art Deco style but they created quite different fashion designs because one tried more of modernistic approach and the other still made frequent use of traditional decorative characteristics.