To provide a design support device capable of designing wiring between cells by effectively using diagonal wiring.

In a net made up of one cell and one or a plurality of cells driven via the output terminal of the one cell, the one cell is used as a driver and the one or the plurality of cells driven by the driver are used as receivers. A position determining function for determining position by determining a predetermined area that surrounds the whole of the one or the plurality of receivers included in each net, and by confirming whether the drivers are located outside of the predetermined area for each net, and a layout function for determining a reference point within the predetermined area for the net where the drivers are determined to be located outside of the predetermined area and for disposing diagonal wiring as wiring connecting the output terminals of the drivers to the reference point when the reference point and the input terminals of the receivers can be connected by vertical and/or horizontal wiring, are achieved by execution of a layout program.