The corporate governance mechanism can help balance the expansion of market power and the maximization of efficiency. This study utilizes the stochastic frontier approach to measure efficiency, and the doubly censored Tobit regression to investigate the relationships among market power, ultimate control rights, and efficiency in the Taiwanese
life insurance industry. The empirical results show that the market power negatively affects efficiency. As the component of ultimate control rights is a moderating
variable, the control right weakens the negative effect of market power on efficiency but cash flow right enhances the negative effect of market power on efficiency. Thus, the findings of this study can serve as a reference for determining resource allocation, formulating marketing strategy and corporate governance policies.