Disclosed is a biped walking mobile system which achieves stability without altering a preestablished gait, and a walk controller and control method therefor. The biped walking mobile apparatus includes a gait former for forming gait data and a walk controller for controlling actions of the drive means based on the gait data. The walk controller includes a ZMP compensator, including: a ZMP sensor, a ZMP converter for computing a ZMP target value based on the gait data from the gait former, and a ZMP compensating stage for comparing the actual measurement value of ZMP detected by the ZMP sensor with the ZMP target value from the ZMP converter to modify the targeted angular velocity and acceleration in the gait data and thereby to compensate or correct the ZMP target value. Thus, the targeted angular path of movement in the gait data remains unaltered when the ZMP target value is compensated.