A judgment section determines whether or not a reduction in the power
dissipation is possible by relocation of an improvement-target cell. If a
reduction in the power dissipation is possible, a calculation section
calculates the delay time of a target path including the
improvement-target cell to obtain a possible shift distance of the
improvement-target cell, within which the timing constraint is satisfied.
A layout change section relocates the improvement-target cell within a
range in which the power dissipation can be reduced and timing constraint
can be satisfied.