The purpose of this study is to investigate the moderating role of operational control systems and reward systems as control systems in the relationship between TQM implementation and firm performance (operational performance) among domestic manufacturing firms, and to determine whether such moderating roles differ by firm size. The research results indicate that operational control systems perform a moderating role as a control system in the relationship between TQM implementation and firm operational performance, whereas reward systems were found not to perform a significant role. Meanwhile, in the utilization of operational control systems, large firms more actively utilized external information systems—which generate and utilize information from sources external to the firm, such as competitors and markets—compared to small and medium-sized enterprises. In contrast, small and medium-sized enterprises utilized internal information systems, which generate and utilize information from sources within the firm, more actively than external information systems, although this difference was not statistically significant. The contribution of this study lies in confirming the necessity for balanced utilization of control systems by subdividing the moderating role of control systems—which must be considered when examining the effects of TQM implementation on firm performance—into operational control systems and reward systems. Additionally, it was confirmed that there are differences in the prioritization of resource allocation necessary for control system utilization depending on firm size.