PURPOSE: To obtain a layout pattern verifying apparatus which can efficiently verify a layout of a large scale LSI in a finite operating region of a hard disk.

CONSTITUTION: Operating region size estimating means 8 calculates a necessary operating region size of an operating region 2 for verifying regarding its layer from data amount of each layer for constituting a layout pattern, and examines the operating region size to be used. Verifying item deciding means 11 selects a verifying item to be executed in the size to be used with reference to the necessary size, forms an executing verifying rule, and stores it in executing verifying rule storage means 10. Layout pattern verifying means 4 verifies the layout pattern according to the verifying rule of the means 10. The selection of the verifying item, the verification of the layout pattern are repeated until all the items are completed. Thus, the verification of the pattern can be efficiently executed.