In Myanmar, almost all RC buildings have been built without national building codes and seismic design consideration. Myanmar still does not have proper seismic evaluation methods and regulation procedures for existing RC buildings. RC structure is a typical and commonly constructed structure of urban cities in Myanmar. Therefore, developing a Seismic evaluation method for existing RC buildings is an important issue for earthquake disaster mitigation in Myanmar nowadays. This paper describes the Seismic Evaluation of existing RC buildings by the Japanese method which is based upon a performance design concept. A case study of the community center building in Tsukuba city, Ibaraki Prefecture, Japan and the lecturer house of Sagaing University in Myanmar was conducted to understand more clearly about the Japanese Seismic evaluation method. There are three different levels of screening to find the seismic capacity of RC buildings in the Japanese standard. In this study, the first and second screening methods were used to evaluate the seismic performance of the Japanese building which had minor damages on the 2011 Great East Japan earthquake and a good correlation observed is described. After that, this method was applied again to our Myanmar RC building and an attempt to adopt this method by modifying into a simple one by using the same concept in combination of the ACI method in evaluation strength is also described. This study was conducted based upon my strong desire to develop a simple method that is compatible to our structures and our engineering society. ACI-318 is already familiar for Myanmar engineers. An easy and a familiar method can be disseminated quickly. Although we have a time limitation, we need a sustainable study to make a perfect method.