The present disclosure relates to a robot teaching system, which moves a robot according to an external force applied from the outside so that the robot has a location and posture intended for teaching and then teaches a location and posture of the moved robot, and the robot teaching system comprises: an arm including a plurality of articular shafts and a plurality of links connected by the plurality of articular shafts; a plurality of strain gauges respectively coupled to frames of the plurality of links to measure a deformation value of the link that is deformed by the external force; and a calculating device configured to estimate the external force from the deformation value of the link obtained by the plurality of strain gauges, calculate a teaching force from the external force and move the robot by an operation corresponding to the teaching force.