A positional information display system includes a control device, a conversion information calculation device and an image information control device, in which the conversion information calculation device has a conversion information calculation portion which calculates conversion information representing a position and/or posture of a first coordinate system on a second coordinate system with a coordinate value of each axis of an industrial machine as a variable; and the image information control device has a coordinate information conversion portion which calculates a position and/or posture on the second coordinate system using conversion information and a coordinate value of each axis; a positional information calculation data setting portion which sets calculation data of positional information for visually displaying the position and/or posture in the first coordinate system by the third coordinate system of a display device; and a positional information display data calculation portion which calculates display data of the positional information.