PURPOSE: To facilitate prediction and the like for a change in a work in process by displaying inputted respective departments and the number of works in process in each department of a product, which is produced in a production line, in a work in process display device for a factory, in which a product is manufactured by a production process carried out via plural departments.

CONSTITUTION: In a CPU 21 of a computer 20, all the departments existing in an external storage device 28 are read from each of department data stored in the external memory device 28, and a display image data, which mainly consists of a command image, a department selection image, a production line selection image, a work in process graphic display image, and the number of works in process display image, is formed to be displayed in a display device 27. When a production line number on the production line selection image is selected by clicking of a mouse, an object production line number is displayed, while an object department number data and a production number data of the object production line are read from the producing condition information stored in the external memory device 28, and then, the number of works in process in the object department is computed by subtracting the termination number of the object department from the termination number of the preceding department and is displayed.