A series of tsunami water tank experiments have been conducted to study global and local tsunami actions on low-to-mid-rise buildings with or without openings and piloti space. Each small-scaled experimental model produced by 3D printer is assumed as a three-story building of square plan with four corner columns and a center core. Wave pressures generated on several portions of external and internal walls are measured to discuss the local tsunami action, whereas wave forces acting on the whole building are measured to discuss the global tsunami action. Numerical analyses have been carried out to simulate the flow of tsunami inside and outside of the buildings and its effect on building structures through the comparison with experimental results. Based on experimental and analytical results, conclusions within this study are summarized as follows: 1) The existence of piloti space reduces the rise of water level and run-up on the front wall. 2) Breaking of glass windows causes the decrease in wave pressure on the external wall and the increase in wave pressure on the internal core wall. 3) Non-fragile windows cause the increase in water level and run-up at the front surface and consequently the rise of water pressure. 4) Maximum wave pressure tends to be generated on the internal core wall rather than on the external wall. 5) Tsunami flowing into the inside of building drains out of side and rear walls depending on flow velocity. 6) Horizontal wave force acting on the whole building decreases by 20 to 35% in the case with openings and piloti space compared to the case without openings and piloti space. 7) The core wall should be taken into consideration as a part of projected area in addition to exterior walls to evaluate horizontal wave force. 8) Vertical force acts downwardly in the case with openings and piloti space, although it acts upwardly in the case without openings and piloti space. 9) Tsunami simulation analysis based on VOF method is effective to evaluate both local wave pressure and global wave force. 10) The spatial distribution and time variation of wave pressure acting on the building and flow velocity inside and outside of the building can be accurately evaluated by tsunami simulation analysis. 11) Vertical force can be reasonably evaluated by slightly floating the building portion from the water bed in the analytical model.