Substrate testing device and substrate testing method

A substrate testing device according to one embodiment comprises the components of a substrate testing unit which is arranged in a substrate testing area for testing the surface of a substrate; a first clamp module which uses the substrate testing area as a reference and is at the upstream side in the substrate conveying direction; and a second clamp module which uses the substrate testing area asa reference and is at the downstream side in the substrate conveying direction, wherein the first testing module moves in a state of a first part of the substrate which exists in a manner of adjacentwith the later moving end of the substrate or exists at the later moving end of the substrate, so that a second part of the substrate which exists in a manner of adjacent with the first moving end ofthe substrate or exists at the later moving end of the substrate passes through the substrate testing area. After the second part passes the substrate testing area, the first part is released. Beforethe first clamp module rele