This study is to develop the well-fit brassieres by observing the changes in the breast sizes and shapes, the surface area of the breast through the arm movements of 3 types (0$^{\circ}$ , 90$^{\circ}$ and 180$^{\circ}$) in vortical motion. The 11 elementary girls who are aged 12 participated in this experiment. To obtain the measures regarding the surface area of the breast, replicas are made at each motion. The results of this study are as fellows: 1. The changes in the breast sizes and shapes at each motion By increasing the motions of the arm movement, the following measure items are inclined to decrease: Shoulder length, Upper blast girth, Bust girth, Under bust girth, Upper bust depth, Bust depth, Under bust depth, Nipple to nipple breadth, Horizontal distance of bust, Horizontal length of the cup, Bust height, Cup size. By increasing the motions of the arm movement, the fellowing measure items are inclined to increase: Center point of shoulder~B.p., Shoulder point~B.p., Center point of shoulder~armpit, Upper Bust breadth, Bust breadth, Under bust breadth, Vertical distance of Bust. 2. The changes in the surface area of breast at each motion By making the replica to observe changes in the surface area, which are sectioned to 4 parts(area 1 to area 4), and volume of breast at each motion, the results are as follows: At 0$^{\circ}$and 180$^{\circ}$, the sizes of each part are ordered as the following: area2>area1>area4> area3. At 90$^{\circ}$, the sizes of each part are ordered as the following: area2>area1>area3>area4. Through these orders, it is found that the upper and inside part of the breast huts the inclination to increase so along as the motions of the arm movement increase. Also, the total surface area increases so long as the motions of the arm movement increase. As a reset of the F-test on the changes in the each surface areas, the surface area by arm movements, the significant differences among the each surface areas are found.