The 2011 Great East Japan Earthquake and Tsunami caused significant changes of morphology of Gamo Lagoon which is located in the northern part of Sendai Coast, Miyagi Prefecture. The investigation on the morphology changes and its recovery process after the tsunami are discussed. Frequently captured aerial photographs are effectively utilized to analyze detailed morphological changes in response to wave action after the tsunami. The lagoon area was greatly changed due to the 2011 tsunami, and a gradual process of river mouth changes and restoration were observed using aerial photographs. As compared with the shoreline position before the tsunami a 40 m retreat of the shoreline can be confirmed even after 3 years from the tsunami. Meanwhile, the water area shows distinct reduction by 40 % as compared with the pre-tsunami situation. Gamo Lagoon is well known not only having important roles in the coastal processes but also valuable brackish water environment, hence further investigation is also largely required to better understand the future state of the devastated coastal environment by the tsunami waves.