The present invention provides a robot system that can easily replace and connect an object robot (robot body or accessory) of the same model or a different model and connect it to the robot controller, and can save it regardless of the type of the robot. Minimize the data of the target robot. A host device that stores model structure information shared by a target robot of the same model for eachmodel is provided, and the target robot is provided with a first storage unit that stores information indicating a model of the target robot, and identifies the individual identification data of thetarget robot and the device-specific data of the individual difference parameters inherent to the target robot. The robot controller detects whether or not there is a replacement with the robot controller of another model by comparing the information indicating the model, and when the replacement is made, the model configuration information of the corresponding model is read from the host device.