A teaching robot including a sensor having a size and a shape which does not deteriorate the accessibility to a workpiece, and carrying out self-teaching of an operation program without execution of actual welding, includes a rotating and sweeping device attached to the distal end of a robot arm, for rotating a noncontact distance sensor; a rotating phase detecting device for detecting rotating phase data; a signal waveform processing device for extracting a feature point from a signal waveform in accordance with distance data to an objective workpiece and rotating phase data; a relationship calculating device for calculating an actual relationship between the objective workpiece and the distal end of the robot arm from feature points extracted from the signal waveform; a relationship setting and storing device for previously setting and storing a reference relationship; and a control device for autonomously moving the robot arm so that the actual relationship calculated by the relationship calculating device coincides with the reference relationship stored in the relationship setting and storing device.