The theory of historical painting materials is a research method that attempts to capture the historical transformation of Japanese culture and society，by reading historical information from visual historical materials，such as picture scrolls and portraits. In this paper，I will take two paintings into consideration，The Portraits of Court Nobles and The Portraits of Toyotomi Hidetsugu’s Family. By analyzing and interpreting the expression of age in group portraits in an iconographical way，I will clarify the characteristics of the age order in medieval Japan.