A robot teaching device for teaching a robot offline, capable of setting target, advance and rotation angles of a tool, so that a flat and stable posture of the tool can be obtained. The teaching device has: a storing part which stores a combination of a plurality of processing portion shapes and the target and advance angles associated with each processing portion; a first setting part which sets the target and advance angles associated with the selected processing portion shape, as target and advance angles with respect to the designated processing portion shape; and a second setting part which rotates the tool about a longitudinal axis thereof while maintaining the target and advance angles, so as to calculate the rotation angle of the tool, wherein a height of a face plate of the robot from a horizon plane in the virtual space is maximum at the rotation angle.