There is disclosed a control apparatus for controlling a plane working robot (1, 1A) comprising a running unit (14) for running on a plane surface, a steering unit for steering the running unit (15) in a predetermined direction, a working unit (13) for performing a predetermined plane working such as cleaning, and a detecting unit (16) for detecting various and actual informations about running direction and distance of the robot and an obstacle on the plane surface, thus permitting the working robot (1, 1A) to take an optimum running path while avoiding an obstacle on the basis of sense outputs from the detecting unit (16) to conduct a work. This control apparatus comprises a working information setting element (21) for setting a working area where the plane working is conducted, and for setting an optimum working running path within the set working area in accordance with a predetermined algorithm, and a working control element (11, 11a) for controlling the running unit and the steering unit (15) so that the running unit (14) allows the robot (1, 1A) to run along the working running path set by the working information setting element (21), and for controlling the working unit (13) so that the robot (1, 1A) conducts a predetermined work during running.