A center of gravity of a robot device is estimated without utilization of a force sensor or the like. An information processing device including a center-of-gravity estimation unit that calculates, on the basis of torque applied to one or more joints included in each of a plurality of leg portions, reaction force applied from a ground contact surface to each of the plurality of leg portions, and that estimates a center of gravity of a robot device including the plurality of leg portions on the basis of the calculated reaction force on the plurality of leg portions.