The purpose of this study is to analyze the efficiency of the Korean life insurance industry from various angles using efficiency-related information provided by Data Envelopment Analysis (DEA) and, on this basis, to specifically identify the causes of inefficiency. DEA, a nonparametric efficiency measurement method, is a technique that measures the relative efficiency of organizations that use multiple inputs to produce multiple outputs, and has been particularly useful in evaluating the efficiency of public and service sectors where price information on inputs and outputs is difficult to obtain. DEA enables analysis of organizational efficiency from various perspectives by providing not only technical efficiency but also supplementary information such as returns to scale, scale efficiency, and optimal production scale. Specifically, this study used data from 33 life insurance companies operating in Korea over an eight-year period from fiscal year 1990 to fiscal year 1997 to determine each company's technical efficiency, returns to scale, scale efficiency, optimal production scale, and changes in productivity indices, and specifically identified the causes of inefficiency in the Korean life insurance industry through cross-sectional and longitudinal analyses. According to the research findings, the Korean life insurance industry exhibited pronounced technical inefficiency due to excessive expenditure on operating expenses resulting from growth-oriented management policies. Specifically, the analysis of efficiency and scale effects for fiscal year 1997 revealed that collection expenses and the number of branches were the primary causes of inefficiency in the Korean life insurance industry. The analysis of the long-term appropriateness of input factor control over the eight-year period from fiscal year 1990 to fiscal year 1997 showed that control was inadequate in the order of collection expenses, new contract acquisition costs, and maintenance expenses. Consequently, individual life insurance companies in Korea need to make efforts to reduce collection expenses and decrease the number of branches to improve their efficiency, and from a long-term perspective, intensive management efforts focused on operating expense components such as collection expenses, new contract acquisition costs, and maintenance expenses are necessary to improve the overall efficiency of the Korean life insurance industry.