The locomotion of legged robots is less effective than that of wheeled robots in a regular terrain. Thus, to improve the locomotion efficiency in a regular terrain, this study presents a small biped walking robot with an auxiliary transportation device consisting of quad roller skates composed of passive wheels mounted on the sole of each foot. An algorithm is proposed to generate skating motion for the robot with quad passive wheels. Skating motion is divided into 6 movements and generated by planning the skating motion based on considering the Zero Moment Point(ZMP). The results indicate that the developed robot is able to generate an effective skating motion.