There are mainly two kinds of methods for pandemic simulations: one is the SEIR model and the other is the MAS model. The SEIR model can deal with simulations quickly for homogeneous populations with simultaneous ordinary differential equations and a few parameters; however, it lacks the versatility in its use. The MAS model can deal with detailed simulations under the many kinds of initial and boundary conditions with standard social network models; however, the computing cost is high. In this paper, we consider a method to combine these two models such that we use the MAS model in the early stage in a pandemic simulation to determine the appropriate parameters that can be used in the SEIR model, and then we use the SEIR model in the subsequent stage with parameters obtained in the early stage. Using this model, we have a possibility to deal with pandemic simulations for the real social structure with less computing cost.