Erosion and deposition by the 2011 Tohoku-oki tsunami in the coastal areas of the Sendai Plain were numerically investigated using the tsunami sediment transport model (STM). The simulation suggested that much of the sediment deposited on land originated from the beach and dune, whereas the contribution from sea-bottom sediments was quite minor. Erosion observed at the backs of engineering structures such as reinforced concrete (RC) dikes was reproduced well in the simulation. Simulated deposition and erosion inside the nearby coastal forest and farmlands were generally consistent with the observed data. Further investigation of the model parameters and implementation of dynamic change in the roughness coefficient and destruction of the structures are required to simulate detailed local variability of erosion and deposition and of the thin sand layer in the inland areas.