This paper presented the investigation of reinforced concrete building structures by 2011 East Japan Earthquake. Generally, reinforced concrete structures in Miyagi region performed very well during the earthquake and effect of seismic retrofit was found in mitigation of damage, although severe damage to some seismically retrofitted buildings was noticed. A good correlation was observed between calculated seismic capacity Is-index and observed damage. Moreover, buildings designed according to the current seismic design code had minor damage in its structural members. However, major damage to non structural elements was commonly observed. Some typical damage observed by author's field survey in Miyagi pref. which is conducted mainly as an activity of the AIJ committee is described. Damage to structural members was not found in most of RC buildings which suffered tsunami, although damage to non structural elements was generally severe. However, severe structural damage induced by devastating tsunami was observed in some buildings.