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 feeding 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, while the teaching unit present signal is outputted, the robot implements the operation program to repeat in the repeat mode in response to an operation start command.