To identify a delamination crack in a CFRP laminate wirelessly, we proposed an electric resistance change method with oscillating circuit in the previous study. Although the method detects the delamination creation, it cannot monitor condition of applied strain before delamination creation because the electric resistance change due to strain changing is quite small. In the present study, a bridge circuit, two amplifiers and voltage-controlled oscillator are added to sensing circuit so that it can monitor very little change of the electric resistance change. Using proposed strain sensing system, the electric resistance change and oscillating frequency change due to strain changing are experimentally measured. As a result, the method is found to successfully monitor the applied strain.