After the launch of PCS in 1997, price competition between five mobile carriers was so severe that the Korean mobile telephony market achieved a remarkable subscriber base growth. But in that optimal pricing behavior depends on how each firm is likely to react to other firms’ choice of price, it is very interesting to analyze competitive pricing behavior and understand market structure in terms of pricing competitiveness in the Korean mobile telecommunications market. In this paper, we use structural econometric models in New Empirical Industrial Organization (NEIO) framework. But previously used models in this framework generally assume that market size is fixed and that all firms maximize their profits. To fit in with the Korean mobile telephony market, we derive various models in using MNL market share model under the assumptions that market size varies with industry’s total attractions and that firms maximize their market share. In this paper, we find that the model under market share maximization with the assumption that market size varies with total attraction shows the best fitting results.