The present invention relates to a testing device for testing an electric state pattern of the substrate, specifically, the clamp for supporting a printed circuit board; A plurality of pins that are attached to each point of the chip mounted on said printed circuit board applying a current; Current supply unit is connected to the clamping pins and a plurality of electrically supplying the current; And is attached to the clamp, as comprising a metal tag in contact with the lower surface of the support a printed circuit board, in particular a substrate with a current to the chip immediately below is applied to the lower surface of the substrate by including a metal tag attached to the clamp It relates to short-circuit defects caused by foreign matter on the surface that can detect device.