Various studies have been conducted to estimate the carbonation suppressive effects of coating materials on concrete. The traditional method for determining these effects uses an accelerated carbonation test of concrete specimens with coating materials. It takes some months to perform these acceleration tests. To evaluate the suppressive effect more quickly, it is necessary to develop a faster and simpler method. In our study, we applied a box method to evaluate the carbon dioxide (CO2) permeability of a variety of coating materials. Moreover, we confirmed the effects that the amount of calcium hydroxide (Ca(OH)2) and the humidity conditions had on carbon dioxide permeability. We found that the permeability of carbon dioxide could be evaluated quantitatively using the box method. In addition, this evaluation was completed within one or two weeks. In conclusion, the box method can evaluate the carbon dioxide permeability quickly and is useful for predicting the carbonation suppressive effect of coating materials on concrete.