As deteriorated track substructures cannot produce enough bearing capacity against the load of the train and may lead to serious accidents, an accurate investigation of the track substructures is necessary for proper repair and maintenance. In this study, a dynamic and static cone penetrometer (DSCP) for characterization of track substructures is developed. The DSCP is dynamically penetrated into ballast layer using a 118 N drop hammer and statically pushed into subgrade. The DSCP consists of an outer rod for the dynamic penetration into the ballast layer and inner rod for the static penetration into the subgrade. At the head of the outer rod, an energy-monitoring module is installed to obtain the transferred energy from the drop hammer and two load cells are installed to obtain the cone tip and friction resistances during the static penetration. As a pilot test, track substructures are simulated in a chamber and the DSCP penetration test is conducted and two field tests are conducted in order to investigate the applicability of the DSCP. From the DSCP tests, the energy corrected dynamic cone penetration index for the ballast layer and static penetration resistances (cone tip and friction resistances) are obtained for the subgrade. This study suggests that the DSCP may be a useful tool for the characterization of railroad track substructures.