A brassier supports and protects breasts and makes a better shape of the upper half of the body through shaping breasts. A brassier, therefore, is recognized as the key underwear for female. Recently, the distribution structure and channels of the brassiere industry is diversified from conventional type of markets to department stores, convenience stores, and internet shopping mall. Studies on the sales of brassieres via internet, however, is not sufficient even though the market size has been dramatically increased thursdays. The study on the size structure (including the size and the materials fabric of brassieres circulating via internet) is especially rare. Therefore, this study tries to comply with increasing requests of consumers through comparing brassier brands on internet. In depth, this study compares cases of Korea and Japan in terms of availability of website on sales, quality indication like materials and functions, and size. The results indicated that there were three companies in Korea which run a website and make a sale through a website. All three Japanese companies operate a website and make sales on a website as well. In terms of size, Korean companies diversify their size of products in two ways. It varies from A cup to D cup based on cup size, and 65 to 100 according to its entire size. On the other hand, Japanese companies use AA, A to I to measure cup size, and 65 to 100 for entire size.