This research was designed to conduct research to apprehend fashion brand's mobile SNS characteristics in depth and the related consumer psychology and behaviors such as brand attachment and brand loyalty. The fashion brand's mobile SNS characteristics were differentiated from the web-based fashion brand's SNS. This study targeted women in their 20s using mobile Facebook and mobile Twitter, and residing in Seoul or Gyeonggi province. Total 412 observations were collected through online survey. The major findings of the study were as follows. First, as the characteristics of fashion brand's mobile SNS, ease of fashion data storage, fashion recentness, fashion usefulness, and fashion accessibility were extracted. As the factors of the flow, time distortion/focused attention and playfulness were extracted. Second, the fashion recentness and fashion usefulness showed positive influence to time distortion/focused attention factor in the flow. All four fashion brand's mobile SNS characteristics showed positive influence to playfulness factor in the flow. Third, time distortion/focused attention factor and playfulness factor both showed positive influence to brand attachment and brand loyalty from using fashion brand's mobile SNS. Fourth, brand attachment had positive influence to brand loyalty from using fashion brand's mobile SNS. Based on the above results, this study provided practical ways to develop effective mobile SNS marketing strategies in fashion brand. Also, this study demonstrated feasible future contents and necessary improvement for fashion brand's mobile SNS, which holds marketing implications.