A　mechanism　model　of　infrasound　producing　in　earthquake　incubating　was　proposed,　in　which　interaction　between　atmosphere　and　deformation　of　Earth　surface　generated　by　dynamic　behavior　of　geologic　bodies　in　the　final　stage　of　earthquake　incubation　causes　the　observable　infrasound.　As　an　example　to　verify　the　model　of　geological　behavior　an　earthquake　in　the　Northeast　area　of　Japan　was　modeled　numerically　and　analyzed　by　two　dimensional　finite　element　method　(FEM).　A　layer　geological　model　and　effect　of　the　Pacific　subducting　plate　were　included　in　the　numerical　model.　Based　on　the　dynamic　coupling　theory　between　structures　and　fluids,　infrasound　owas　obtained　by　numerical　simulations.　Good　agreement　between　the　observed　and　the　simulated　suggests　that　the　proposed　model　is　reasonable.