We developed a tsunami inundation forecast system which can estimate the tsunami inundation area in real time by seismic and tsunami information. We were able to obtain the tsunami observation data of the GPS buoy as well as inundation by the 2011 Tohoku earthquake. Firstly we verify the system in Sendai and Ishinomaki by using the database with developed before 2011. Agreement with the observed inundation in Sendai is fine but not at Ishinomaki because limitation of earthquake magnitude and location assumed in the system. Therefore, we reconsidered this system and the revised system is applied to Ishinomaki. The result of inundation is improved but calculated inundation at some area is overestimated. So that we selected the location of GPS buoy more closer to Ishinomaki, then the result is again improved.