[Purpose] The Gait Judge System measures the plantar flexion resistive torque acting on the angle of the ankle joint, as well as the ankle joint itself, of the ankle-foot orthosis using a 1,000 Hz sampling frequency. This pilot study aimed to determine the characteristics of plantar flexion resistive torque acting on the double Klenzak ankle joint of the ankle-foot orthoses worn by healthy individuals. [Participants and Methods] Participants were eight healthy young adults (3 male, 5 female; mean age, 26.8 years old; mean height, 165 cm.; mean body weight, 56.3 kg). Plantar flexion resistive torques and angles of the ankle joint in gait cycles were measured with the Gait Judge System. Speed of gait was calculated using a ruler attached on the floor and the Gait Judge System video. We classified waveforms according to the existence of second peaks in the gait cycle. The correlations between parameters related to the plantar flexion resistive torque and the speed of gait were evaluated using Pearson’s simple correlation analysis. [Results] The plantar flexion resistive torque showed two peaks: the first peak was at the loading response, measured at 17.4 Nm, and the second peak was at the pre-swing phase, measured at 10.9 Nm. However, the second peak was absent in three of the participants. The normalized second peak and the second peak/first peak ratio had a strong, positive correlation with the speed of gait. [Conclusion] The Gait Judge System revealed typical waveforms according to the parameters set in this study.