Abstract: In this testing device, a space in which a transistor 117 is disposed and a space in which a driving circuit for testing is disposed are separated by a partition wall 214. The driving circuit has a plurality of switch circuit boards 201, and a conductive plate 204 for connection is attached to the switch circuit board 201. A fork plug 205e is connected to a collector c terminal of the transistor 117 to be tested, and a fork plug 205c is connected to an emitter e terminal. The insertion of the fork plug 205 into an opening 216 provided in the partition wall 214 allows the connection of the fork plug 205 and the conductive plate 204. By changing the position of the opening 216 for inserting the fork plug 205, the connection to the driving circuit can be changed in accordance with an item to be tested.