1. A robot system comprising: a robot; a robot controlling unit which controls an operation of the robot based on an operation program in a repeat mode; and a teaching unit which implements mutual transmission and reception of information with the robot controlling unit with a wireless connection; wherein the robot controlling unit comprises, a feeding unit which feeds a power to the teaching unit, and the teaching unit comprises, a power receiving unit which receives the power from the feeding unit, and a battery which is charged with the power received by the power receiving unit, the feeding unit comprises a teaching unit detection device which detects that the teaching unit is disposed in a predetermined position of the feeding unit, when the teaching unit is disposed in the predetermined position of the feeding unit, the feeding unit supplies the power to the teaching unit and outputs a teaching unit present signal from the teaching unit detection device, only while the teaching unit present signal is outputted, the robot executes the operation program to repeat in the repeat mode in response to an operation start command when the teaching unit present signal is not outputted the operation program can not operate the robot in the repeat mode, thereby providing enhanced safety to an operator wherein the teaching unit comprises a non-contact information transmission device in which a predetermined information is recorded, the teaching unit detection device comprises a detector for reading the information recorded in the non-contact information transmission device, and the teaching unit detection device outputs the teaching unit present signal based on a verification result of a detector read information and a preset information.