The invention provides a floor planning technique by which physical blocks having areas sufficiently matching with actual sub circuits can be produced automatically and also a physical block of a shape other than a rectangle can be produced using a very simple technique. To this end, a floor planning apparatus of the invention includes a circuit unit recognition section for recognizing circuit units which compose each of the sub circuits, a part information storage section for storing, for each of the circuit units, numbers of parts of different part types which compose the circuit unit, a part number calculation section for acquiring, for each of the different part types, the numbers of the parts composing the circuit units recognized by the circuit unit recognition section from the part information storage section and calculating, for each of the different part types, total numbers of the parts in each of the sub circuits, and an area calculation section for calculating and determining an area of the physical block based on the total numbers of the parts calculated for each of the different part types by the part number calculation section. The invention can be applied to designing of a circuit such as an LSI (Large Scale Integration) and a PCB (Printed Circuit Board).