The enormous tsunami damage from the Great East Japan Earthquake revealed the problems in the forms of tsunami disaster prevention and mitigation measures at that time. Underestimation of tsunami estimation and tsunami warning, as well as delays in understanding disaster situations, have especially been recognized as factors leading to the increase in scale of disasters, and are important issues requiring urgent reforms. Building on the lessons learned from the Great East Japan Earthquake, I will here introduce the new measures for tsunami disaster prevention and mitigation already being put in place ahead of the next disaster.