A testing device to test a plate for electronic circuits, comprising transport members able to transport the plate along an axis of feed (Y), at least from an entrance station to a testing station defining a testing plane (P′), and testing members, disposed in correspondence with the testing station. The testing device also comprises an alignment station defining an alignment plane (P), disposed upstream of the testing station, and alignment members, disposed in correspondence with the alignment station, able to dispose the plate in an aligned position, in which the plate is disposed symmetrical both with respect to the axis of feed (Y) and also with respect to a first axis (X) substantially transverse and co-planar to the axis of feed (Y).