An object of the present invention is to provide a robot apparatus and a walking control method thereof capable of changing walking control modes in accordance with floor surfaces by discriminating states of the floor surfaces for walking without modifying a step-based walking schedule and capable of providing stable walking even if floor surface states change greatly.A robot apparatus comprises: an action control section 11 to output a walking start instruction; a floor surface discrimination section 12 to discriminate a category for a current floor surface; and a walking control section 13 to compute an adaptive operation amount. The walking control section 13 obtains sensor values of a foot sole sensor and the like from the current floor surface by means of an in-place stepping motion and the like. Based on the sensor value, the walking control section 13 computes the adaptive operation amount as a correction amount from a standard gait model. The floor surface discrimination section 12 performs pattern recognition for the adaptive operation amount to discriminate the category for the current floor surface. The walking control section 13 is supplied with the floor surface category and selects an optimum walking model for the floor surface category. Again from the sensor value, the walking control section 13 computes the adaptive operation amount as a correction amount for the sensor value and provides walking control accordingly.