Recently there has been considerable interest in anomalous transport in porous media. An Advection-Dispersion Equation (ADE) is widely used as a governing equation of contaminant migration, however there have been a number of reports that ADE does not express observational and experimental data. This clear discrepancy is attributed to insufficient knowledge about the mechanism of anomalous transport. The primary objective of this study is to present the possible mechanism of anomalous transport analytically by investigating the effect of viscosity on the dispersion process from the equation of Continuous Time Random Walk (CTRW). In addition, a method, which predicts contaminant migration not only in homogeneous material but also in heterogeneous material, has developed by combining the clarified mechanism and streamline method. Streamline is discretized to infinitesimal passes and CTRW which describes contaminant transportation is numerically integrated in the passes. Results obtained from the developed method have agreed well with experimental results of this research.