A total floor reaction force required correction amount by which an error between an observed value of a total floor reaction force acting on a mobile object 101 and a desired total floor reaction force approaches zero is converted to a spring displacement amount of a position/posture of a representative contact surface representative of ground surfaces of the mobile object 101. A correction amount of a displacement amount of each joint of the mobile object 101 is determined by multiplying the spring displacement amount by a pseudo inverse matrix of a Jacobian matrix representing a relation between a change amount of the position and posture of the representative contact surface per unit time and a change amount of a generalized variable vector per unit time. The displacement amount of each joint is controlled according to a corrected desired joint displacement amount obtained by correcting a desired joint displacement amount.