The electric resistance method for detection of the internal delamination in laminated carbon-fiber-reinforced polymers composite material has been explored in the paper. The effect of spacing between electrodes on the crack detection efficiency has been investigated. The problem has been solved by the method of planning of the experiment and response surface method by using 2-D finite element model. The distance between the electrodes and the crack length have been selected as the parameters of the study. The results of the numerical solution have been obtained by using the four probe method of measurement of the surface and oblique electrical resistance. The optimal distance between the inner and outer probes for the effective detection of the crack and delamination has been determined. The influence of the distance between the internal and external probes has been identified to have greater effect on the detection of the crack than the distance between the internal probes.