An industrial robot having an expansion axis, a turning axis and a vertical axis, wherein the one end of flexible supporting plate supporting an internal wiring and piping system of the robot is fixed to the expansion axis which is capable of making free linear motion for a base plate arranged to the vertical axis. The flexible supporting plate is bent in the form of letter U in parallel to the turning plane of the expansion axis. Therefore, the expansion axis can be located at the sufficient lower position for the base plate, and the strength and accuracy of the drive mechanism can be improved.