As　already　reported,　practical　calculating　method　was　suggested　for　the　long-term　deflections　of　reinforced　concrete　slabs　and　prestressed　reinforced　concrete　slabs.　The　application　of　this　method　is　limited　to　one-way　slabs.　On　this　study,　it　was　suggested　that　the　calculating　method　of　two-way　slabs.　The　effects　of　various　factors　on　the　deflection　of　slabs　are　numerically　analyzed,　and　the　points　of　concern　for　control　design　of　long-term　deflections　were　indicated.　In　addition,　the　usability　of　the　control　method　of　long-term　deflections　was　shown.