Irie Tomotoshi (1718-99), a younger brother of Sumitomo Tomomasa who was the fifth head of the Sumitomo, was the founder of the Izumiya Rihei house as a branch family of the Sumitomo which run money exchange business. He studied in his youth at the Kaitokudo school, a famous private school of the teaching of Confucius, and learned from Goi Ranshu there. Irie Tomotoshi functioned as the manager of the Sumitomo main house for his brother, Tomomasa, who was weakend by illness, and made many reforms in the house management. Among the reforms, codification of the Sumitomo house laws was of special importance. Tutomekata-cho was one of the house laws written in 1760 by Tomotoshi and was concerned with the labor management practice in the Sumitomo. The purpose of this paper is to introduce and to interpret Tutomekata-cho, aiming at clarifying Tomotoshi's personality and his achievements in the history of the Sumitomo.