This study is aimed at comparing earthquake resistance capacity evaluated by using diagnosis program with actual earthquake damage for existing reinforced concrete buildings， which were constructed before developing “New Earthquake Resistance Design Method” in 1981. An earthquake resistance diagnosis program was made using spreadsheet software (MS-Excel). The program has visually checking worksheets in order to explore input errors. The 3-story library building of Hiroshima Institute of Technology，which was damaged in the second-floor columns due to the 2001 Geiyo earthquake，was tried to check results of the first diagnosis and the second diagnosis. A commercial diagnosis program (Super Build) was also used to compare accuracy of both programs. The actual damage was suffered at the second-floor columns， however values of the seismic index of structure，Is，from the diagnosis program show that the first is the most severe floor. Torsion effects should be checked for more realistic earthquake resistance capacity of structures.