PURPOSE: To make the number of times of arrangement work of replacement of tools minimum, by deciding the layout of the tools based on data of working results.

CONSTITUTION: The titled device is provided with working results 13 of combination of tools necessary for processing of a work in an NC device and a memory 11 for storing a utility probability of a layout module of each of tools and the layout module of the tool to which the combination of the tools is to be intensified and consists of a computor 10 treating input information by making use of the same to a predetermined program, an input terminal equipment 22 applying the combination of the tools necessary during processing of the work to the computor 10 and a terminal equipment 23 for displaying the layout module of the tools to be put out from the computor, the layout module of the tool through which the combination of the tools put in from the input terminal equipment is to be intensified is decided based on the working results of the combination of the tools and the utility probability of the layout module of the tools, in the memory 11, and the results of them are displayed.