In order to improve the understanding of earthquake resistance characteristics of prestressed concrete (PC) structures designed by the current design method (route-3a), the following researches had been performed : (1) Determination of earthquake load, dead or live loads and indeterminate force in design. (2) Comparison between ultimate strength of PC beam, strength developed by PC bars in the PC beam section and required strength of beam in design. (3) Comparison between ultimate strength of columns and required strength of column in design. (4) Static elasto-plastic analyses of designed frame. The main result of this study is that equipment of PC bars in beam section is not a factor in over-strength against required strength in design and PC frame structure has the story whose shear strength is lowest of all stories in the structure essentially and this feature is caused by the large dead or live load of the structure.