In traditional costume, colors have been used to express the religion, society, culture, custom, and other aspects of a country. This is mainly due to color being the most conspicuous visual factor of a costume. In Thailand, there is a symbolic color for each day of the week, and the purpose of this study is to contribute to deeper understanding of the Thailand culture in regards to color and its costumes. The study method is as follows: literatures and photos were researched for social and religious background of the seven days Buddha history, which was the source of the color a day culture, symbols and significance of each Buddha were studied and precedent studies were reviewed. The study attempted to investigate the effect of the symbolic color on costumes as it passed down from generations. Originally, the symbolic colors of seven days Buddha in Thailand was a religious component that was exclusive to the upper class. However, it has expanded to the lower classes today. Currently, it obtains an aspect of health and wealth gospel for oneself or others as well as being used to express individual personality because people regard certain color as their symbolic color.