Characteristic features of the pion-condensed phase are studied in the σ-model by introducing new variables. For the neutral pion-condensed phase the pion field is defined as a chiral angle and the coupled field equations are derived in the mean-field approximation. The structure of the nucleon system in the condensed phase is investigated on the basis of these equations. It is shown that the Alternating-Layer-Spin structure is surely realized in the σ-model. The validity of Dautry and Nyman's model is also discussed.