As many firms adopt chain operations, it is worth investigating whether the operations are efficient enough to support the firm’s growth and if opening new retail outlets actually provides economies of scale. This study examines the effect of increasing the number of stores on retailers’ operational efficiency and tests the effect empirically. The number of stores is considered an important indicator affecting retail efficiency. However, previous studies have returned conflicting results and arguments about the impact of the number of stores on efficiency. A log-linear regression analysis reveals that while retailers gain advantages in terms of reduced purchasing costs, they increase the costs for store operations. This paper aims to contribute to the field by clarifying the impact of retailers’ growth on operational efficiency based on empirical research.