Tsunami activated by earthquake is known to be one of the most powerful natural disasters. For instance, in March 11, 2011, tsunami activated by earthquake led to several compound disasters in Japan. Many coastal protection structures such as seawalls and breakwaters were found to be damaged seriously. In order to protect coastal structures from such kind of devastating damage in the future, it is essential to take proper countermeasures. A tire retaining wall in Iwate prefecture located just about 150 m away from a completely collapsed sea wall was found to be neither scoured nor damaged by tsunami, which indicates that the flexible tire structure has a great potential to reduce the tsunami impact force as compared to heavy and rigid structures. Therefore, main object of this research was to demonstrate how effectively tire structure will function against the earthquake and tsunami to protect sea wall from scouring on the foundation and resulting damage. A new model for simulation of tsunami impact force has been developed in Geotechnical Engineering Laboratory of Kyushu University. In which absorption of tsunami impact force and the dispersion effect of the tire structure was examined. Field experiments were also performed with various types of plants cultivated inside the soil-filled tires to see how the greening effect could be maintained. Results showed a better performance of the sea wall when protected with tires placed behind the sea wall. Also, field test showed that the greening effect could be maintained by cultivating suitable plants inside the tires.