A local bond stress-slip relationship between the reinforcing steel and concrete is one of main factors in numerical calculation of crack widths in reinforced concrete members. And calculation methods of crack widths under tensile load condition have been presented by many authors from point of the bond-slip relationship. The calculation method of crack widths under unload and re-compressible load, however, is insufficient. Hence, after authors studied behavior of crack widths from effect of restraint between steel and concrete by repeated loading test, a new calculation pro-cedure of remaining crack widths is proposed considering of exis-ting bond-slip relationship. Further, axial tensile load tests of reinforced concrete member were carried out to know followings; effect of post-tension on initial crack widths, behavior of the cracks after repair by infusion method, and validity of new calculation procedure.
　Remaining crack widths were decreased substantially by post-tension through the loading test. And crack widths were fixed by repair of infusion method, and no effect of load on crack widths after repair was observed. It is proved that a new calculation procedure gives safety to remaining crack widths in design.