This paper presents bimodal mobility actuated by inertial forces with elastic bodies for an exploration robot in a microgravity environment. The proposed bimodal locomotion mechanism can selectively achieve vibration propulsion or rotational hopping mode based on centrifugal force and reaction torque exerted by the control of a single eccentric motor, where the rotational hopping is the primary locomotion mode for practical applications. The bimodal mobility performance under microgravity is experimentally examined using an air-floating testbed. Furthermore, we also present theoretical modeling of the bimodal mobility system, and the model is verified by comparison with the experiments.