This thesis aims to investigate the morphologic relationship among the neckline, collar, and hair style, in which the width and height were measured by selecting the representative costumes from 16th to 19th centuries. The pieces of 170 pictures selected by fashion experts were cut in the same condition, with the part of the end of shoulder, head, and chest all placed on the equal level. The products were directly measured by a team of 3 specialists for verification of this study, of which results were calculated into average. The values of output were categorized into the unit of decade and finally into a graph of variation, in which the trend and relationship were evaluated according to the width and height. In 16th century, the width and height of the neckline were inversely proportional to those of hair style, while those of collar were proportional to those of hair style. In 17th century, the width and height of the hair style were proportional to those of neckline and collar. In 18th century, those of the neckline were inversely proportional to the hair style, with no collar found. In 19th century, the width of the neckline and collar were proportional to that of the hair style, while the height of the neckline and collar were inversely proportional to that of the hair style. The analysis of the morphologic relationship among neckline, collar, and hair style resulting from this study revealed that the change of the hair style took place corresponding to those of neckline and collar. Generally, the width of the hair style was found to be more resistant to change, compared to those of neckline and collar that were more susceptible. The height of the neckline was more resistant to change, compared to those of the hair style and collar presenting their frequently fluctuating height. Conclusively, the factor of height rather than that of width showed more dominant proportions, because the various forms of the collar and hair style evolved in terms of the height rather that width, relative to that of the neckline.