PURPOSE: To hardly carry noise on a wired signal layer by using only one of the two layers as a wiring layer and the other layer as the GND-wiring, in the signal layers in which two layers are wired as one set.

CONSTITUTION: Signal wiring layers 1, 2 are wired as one set. Normal wiring is provided in one layer 1 of the layers 1, 2. Wirings are provided all in one direction of the wiring direction of a wiring channel to be used as main of the layer 1 to be normally wired of the other layer 2. The wirings provided all in one direction of wiring channel, are connected to a GND 8. Further, a land 7 of a size to be short-circuited to the wiring channel to be wired is provided for a GND pin for the layer 1. Thus, noise is hardly carried on the wired layers 1, 2.