A robot apparatus includes a robot having a swingable arm, a wrist mechanism mounted on the arm, and a running mechanism for displacing the robot in a prescribed direction. The wrist mechanism is coupled to an attachment member by an actuator having a fluid cylinder substantially parallel to the arm. When a component to be attached to a workpiece is held by a jig mounted on the wrist mechanism, the fluid cylinder is actuated to lift the wrist mechanism in order to correct the jig for the distance it is lowered due to the weight of the component. The wrist mechanism includes a bracket mounted on the arm by a support shaft, the bracket and the support shaft having fluid passages for supplying fluid under pressure to a torque actuator disposed in the bracket. The running mechanism is disposed in a pit defined in a floor on which the robot apparatus is located.