A semiconductor integrated circuit design apparatus includes: an association information creating unit which creates association information for associating wiring information of a signal line with wiring information of a shield line placed for the signal line; an association information storage unit which stores the thus created association information; and a shield wiring unit which, when the placement of the signal line is changed, changes in interlinking fashion with the changed placement the placement of the shield line that is associated with the signal line by the association information.