We analyzed the backscattering characteristics of TerraSAR-X, ALOS PALSAR, and RADARSAT-2 data to observe agricultural areas damaged by the tsunami triggered by the 2011 off the Pacific Coast of Tohoku Earthquake. Agricultural parcel data were overlaid, and mean backscattering coefficients were extracted from each parcel. We compared data obtained from different sensors collected on the same day. TerraSAR-X and RADASAT-2 acquired on March 12, 2011, show similar behavior. TerraSAR-X and ALOS PALSAR data obtained on March 16 and 23 were also analyzed. Correlation coefficients of TerraSAR-X and ALOS PALSAR are smaller than those of TerraSAR-X and RADARSAT-2. The present study illustrates that is possible to estimate flooding area by tsunami using the TerraSAR-X, RADARSAT-2, or ALOS PALSAR data. The effect of the observation wavelength on the analysis results is examined.