1. A robot control system having a robot, a portable operating device that is actuated by a rechargeable secondary battery and used to operate the robot, a robot control device that is capable of wirelessly communicating with the portable operating device and performs automatic operation of the robot based on teaching data input by the portable operating device, and emergency stop means that causes an emergency stop of the robot when wireless communication between the portable operating device and the robot control device is interrupted, the robot control system comprising: a charging device, wherein the charging device is configured to charge the secondary battery when the portable operating device is electrically connected to the robot control device; a connection monitoring section configured to monitor whether an electric connection between the portable operating device and the robot control device through the charging device is established; a disconnection detecting section that detects whether the portable operating device is disconnected from the robot control system; a date and time obtaining section for obtaining a date and time of when the portable operating device was disconnected from the robot control system; a charging amount obtaining section for obtaining a charging amount of the secondary battery at the time when the portable operating device was disconnected; a display means that displays a message informing a reader that the portable operating device is disconnected from the robot control system and that displays at least one of the date and time and the charging amount when the portable operating device was disconnected; a display processing section, wherein the display processing section generates display data, and wherein the display data is transmitted from the display processing section to a display section of the portable operating device where it is displayed; and an automatic operation continuing section, wherein if the connection monitoring section detects that the electric connection is not established when the robot is in automatic operation, the automatic operation continuing section ends wireless communication without causing an emergency stop of the robot and continues automatic operation of the robot with the portable operating device disconnected from the robot control system; wherein, in response to the automatic operation continuing section ending wireless communication, the automatic operation continuing section sends a signal to the display processing section for suspending generation of the display data such that the display processing section changes the destination of transmission of the display data from the portable operating device to the robot control device, wherein display data continues to be generated on the robot control device when wireless communication has ended.