The purpose of this paper is to study the dynamic behavior of soft ground including aporous layer by considering the porosity change.In order to take the porosity change into account,theconcept of the volume fraction,which has been proposed in continuum mechanics,is introduced.Theconstitutive equations presented by Bowen are applied to the analysis of the porous media.According toBowen’s theory,the porosity is considered as a variable called the volume fraction and has its own consti-tutive equation.The constitutive equation of the volume fraction has thermoelastic equation coefficientsand is determined by the strains of the solid and the fluid.This means that the compressibilities of the solidand the fluid are considered.When the special condition is assumed,Bowen’s theory can contain Biots’stheory,which has been applied in earthquake engineering.The wave propagation in the ground includinga porous layer,modeled by Bowen’s theory,is studied and compared with that of Biot’s theory.One-di-mensional attenuation and surface amplitude are calculated.The effect of the volume fraction is discussedwith respect to the compressibilities of the solid and the fluid. The purpose of this paper is to study the dynamic behavior of soft ground including aporous layer by considering the porosity change. In order to take the porosity change into account, theconcept of the volume fraction, which has been proposed in continuum mechanics, is introduced. Theconstitutive equations presented by Bowen are applied to the analysis of the porous media. According to Bowen’s theory, the porosity is considered as a variable called the volume fraction and has its own consti-tutive equation. Constitutive equation of the volume fraction has thermoelastic equation coefficients and is determined by the Danger of the solid and the fluid. This means that the compressibilities of the solid and the fluid are considered.When the special condition is assumed, Bowen’s theory can contain Biots’stheory, which has been applied in earthquake engineering. The wave propagation in the ground including a porous layer, modeled by Bowen’s theory, is studied and compared with that of Biot’s theory. One- di-mensional attenuation and surface amplitude are calculated. the effect of the volume fraction is discussed with respect to the compressibilities of the solid and the fluid.