Abstract: A robot apparatus that is able to perform jumping. In a leg structure 110 of the robot apparatus, connecting bars 113, 114 and pivots 112a to 112d constitute a four-point link mechanism. A rod 117 is inserted into an opening formed in the distal end of a leg part 116. A coil spring 118 as an elastic member is provided between one end of the rod 117 and the distal end of the leg part 116. A bar member 120 is connected and secured to a preset point of a connecting member 115 as a knee joint. The coil spring 118 is extended/contracted by the stretching/contraction of the connecting member 115. By the operation of the four-point link mechanism, the trajectory of the distal end of the leg part is linear. The coil spring 118 is mounted at a position such that the distance between a driving shaft 101 and the distal end of the bar member 120 has a substantially linear relationship with respect to the force virtually operating between a driving shaft 101 and the distal end of the bar member 120.