There is provided a technique in which internal wires of a large cell are spuriously patterned and treated as object of a noise check. Internal wires of a large cell are spuriously determined based on terminal information and wiring forbidden information of the large cell and are added to chip wires to be checked, from which an object wire to be checked and at least one affecting wire are selected, a noise value representing a degree at which the at least one affecting wire induces noise onto the signal of the object wire is calculated and the noise check is performed on the basis of the calculated noise check.