A robot apparatus having a robot and a controller for controlling the robot. The apparatus has a diagnosing computer connected to the controller and acquiring a state quantity of the robot. An analyzing computer is provided remotely from the robot and has a control parameter adjuster for adjusting a control parameter of the robot, and a communicating function of connecting the computers. The state quantity is transmitted to the analyzing computer by the communicating function and a control parameter of the robot is obtained based on the state quantity. The control parameter is transmitted to the controller through the diagnosing computer to control the robot.