A semiconductor device is made up of a first insulating layer having a through hole; a first interconnection which comprises a first conductive layer, a first barrier layer, and a first main interconnection, and a second interconnection connected to one of the first conductive layer and the first barrier layer. Accordingly, the semiconductor device can avoid a problem so that the Cu of the first main interconnection transfers from a portion connected to the second interconnection due to cause electromigration, the connected portion becomes a void, and the first interconnection is disconnected to the second interconnection.