A method includes: forming an imaginary wall at a position spaced apart and outward from feet of the robot when the robot is in a double-leg-support state; kinetically calculating a variation in a distance between a body of the robot and the imaginary wall and a variation in a speed of the body of the robot relative to the imaginary wall using an angle of a joint and lengths of links of the robot; applying the variation in the distance and the variation in the speed to an imaginary spring-damper model formed between the body of the robot and the imaginary wall, and calculating an imaginary reaction force required by the body of the robot; and converting the calculated reaction force into a drive torque required by the body of the robot using a Jacobian transposed matrix.