Placement is performed by using a library created by enlarging cell frames
of at least one type of cells out of a plurality of types of standard
cells constituted by using transistors having different characteristics
for the respective types of cell. More preferably, the overlap between
cells is judged by using unenlarged cell frames as adjacent boundaries
for standard cells of the same type, and the overlap between cells is
judged by using enlarged cell frames as adjacent boundaries for standard
cells of different types. This enables automatic placement in which
different types of cells are mixed.