In this study, a function to estimate tsunami inundation depth using pre- and post-event high-resolution synthetic aperture radar (TerraSAR-X) data was derived and the performance was evaluated. After the tsunami disaster, it is important to identify an extensive impact caused by a tsunami disaster. Tsunami inundation depth is an important index to expect building damage because it has a strong correlation with the amount of building damage. However, it was diffcult to estimate the tsunami inundation depth from satellite image. This study aims at developing a method to estimate tsunami inundation depth by integrating remote sensing technology and tsunami engineering. The method for estimating tsunami inundation depth consists of two steps, 1) Change detection of pre- and post-event TerraSAR-X data that captured affected areas due to the 2011 Tohoku earthquake and tsunami, 2) Estimation of tsunami inundation depth. The new function showed good performance with the correlation coefficient of R = 0.68.