This study analyzed Korean middle-aged men's fashionable styles according to ageless trends as their representative characteristic and deriving their special features from men's magazines. Literature and case studies were conducted together. The research findings are as follows. First, it showed uniformity, conformity, passive clothing selection and consumption in 1990s as characteristics of middle-aged men's wear by period. However, clothing became an expressive way to pursue individuality and an ageless trend gradually, and middle-aged men positioned themselves as subjects of a consumer market for men's wear after 2010 through active clothing selection and consumption. Second, along with a trend change preferring a comfortable and active to formal atmosphere, it showed that casual style became diversified and segmented gradually in Korean middle-aged men's ageless trend and fashionable style. Third, as for formative characteristic changes in middle-aged men's fashionable style by period, it contained a slim silhouette, bright and splendid colors and patterns, increase of light, active and functional materials, generalization of casual items and pursuit of individuality by various mix & match styles. Fourth, in Korean men's ageless trend and changing fashionable style, four kinds of special characteristics were derived that included a change of the traditional clothing symbolism, weakened conformity & pursuit of personality, obscured boundaries between age and wearing style, and active embracing of a trend.