A perfobond strip is widely used as the validated shear connector in various steel-concrete hybrid structures. In general, the penetrating rebar is arranged in the perforation to suppress the brittle fracture of the perfobond strip due to the shear failure of the concrete at the perforation. However, the effect of the penetrating rebar on the shear resistance, and the effect of the perforation diameter, the penetrating rebar diameter, and the thickness of the steel plate on the behavior of the penetrating rebar have not been clarified until now. In this research, in order to investigate the effect of the penetrating rebar on the shear resistance of the perfobond strip, simple push-out tests were conducted paying attention to the relation between the perforation diameter and the penetrating rebar diameter, and the variations in the steel plate thickness. Furthermore, to obtain the shear contribution of the penetrating rebar to the shear resistance of the perfobond strip, a nonlinear numerical analysis was conducted. As a result, a design formula was constructed to evaluate the shear resistance of the perfobond strip with the penetrating rebar.