A circuit layout design method capable of an LSI circuit or an electronic printed
circuit board free of electromagnetic interference is provided. The layout design
method according to the invention includes a quasi-stationary circuit reduction
step of deviding an entire circuit represented by a net list and a part library
into a plurality of quasi-stationary closed circuits having a reduced size so that
an intensity of an electromagnetic wave radiated from each of the quasi-stationary
closed circuits is not more than a predetermined value; a wiring constraint condition
calculation step of calculating constraint conditions for each of wirings mutually
connecting the plurality of quasi-stationary closed circuits so that the intensity
of the electromagnetic wave radiated from each of the wirings is not more than
the predetermined value; and a layout step of laying out parts and the wirings
based on the net list and the parts library so as to satisfy the constraint conditions.