Abstract: The present invention is concerned with an apparatus for inspecting the operation of a number of integrated circuit devices mounted on a printed circuit board. The apparatus includes a common lead-out connector unit that may be connected to and used with any one of a plurality of fitting units adapted for separately fitting to a plurality of the integrated circuit devices having a variable number of lead terminals for taking out signals at the integrated circuit devices. The apparatus makes it possible to take out signals simultaneously at all of the lead terminals of the integrated circuit devices for inspecting the operation of these devices for elevating the inspection efficiency of the integrated circuit devices having a variable number of the lead terminals.