The modifiable design of clothes is significant in that a single garment can be presented in various ways and can be modified by user adjustments as well different kinds of figurative beauty can be expressed through the garment. This study departmentalized the case of knitwear in the modifiable design of clothes to propose a possibility of a variable knit fashion that makes the most of the knit characteristics. This study investigated precedent research, arranged general terms, created fundamental notions, found the background of the advent, and located specific characters in the modifiable design as well as arranged a concept, type, structure, and traits for the knit. The following results were obtained through this study. First, the modifiable design of the clothes can express the change of the silhouette and the change of the item itself or a change in the item according to the change in the mode of wearing, manipulation, and technology. Second, the results show that modifiable knit designs by open & close are mostly used according to manipulation and have no existence in this study according to the technology. Third, there was a noticeable appearance of a modifiable knit design from 2002 to 2004. However, it was increased again in 2009 after a steady decrease in 2005 and 2008. Finally, it can create effects in several dresses in the visual aspect and functional aspect.