Head injuries are the most common cause of pedestrian deaths in car-pedestrian accidents. To reduce the severity of such injuries, the International Organization for Standardization (ISO) has proposed subsystem tests in which child and adult head-form impactors are impacted upon a car bonnet top. The ISO designated the mass of the child head-form impactor as 3.5 kg (i.e., the average mass of a 6-yearold child’s head), and that of an adult as 4.5 kg. However, such head-form impactors have not been developed so far. Therefore, in the present study we report the development of new child and adult head-form impactors according to the requirements of the ISO subsystem test procedures. The technical specifications, including the location of the center of gravity, the location of the seismic mass of accelerometers, the moment of inertia, and first natural frequency of the impactors, were summarized. Then, the results of biofidelity certification tests of the skin of these newly developed impactors were investigated.