Many coastal structures have been destroyed by the tsunami in the 2011 Tohoku Earthquake and urgent countermeasures against the tsunami are desired. The tsunami evacuation buildings can be one of effective countermeasures and tsunami force and tsunami run-up height on the buildings have been studied using impermeable structures. However, effect of windows and other openings, location of walls may have significant effect on tsunami forces and run-up. This study is intended to investigate effect of configurations of building structure on them. Tsunami force is found to be reduced in the case that impermeable wall inside building is set landward. Moreover, this paper shows that it is possible to estimate the tsunami force on buildings considering openings of the outer wall and configuration of inner walls.