This study addresses the problem of uncertainties of total CO2 emission intensities estimated using an input-output (I-O) table for a life-cycle inventory analysis. The validity of the total CO2 emission intensities has been questioned mainly because the amounts of commodities are measured in monetary units, and because various commodities are produced in a single sector of an existing I-O table. In this study, first. a sensitivity analysis of total CO2 emission intensities estimated using the Japanese I-O table was performed to identify the elements that significantly influence the total CO2 emission intensity. If an influential element identified by sensitivity analysis varies widely, the total CO2 emission intensity is greatly influenced. Secondly, how much total CO2 emission intensities vary associated with the variation of those influential elements as evaluated. It was concluded that the evaluation of uncertainties using a stochastic approach as well as the improvement of accuracy by disaggregating the original I-O sectors, focusing on influential elements, are important.