PURPOSE: To increase the packaging density and reduce the size and manufacture cost by laminating plural unit wiring boards which form a plate shape and have a function of making and breaking plural contacts and thus forming a three-dimensional network, and moving forth and back a decoding bar through each actuator and connecting the 1st optional connection terminal to the 2nd connection terminal selectively.

CONSTITUTION: The main wiring board device is constituted by laminating 2n unit wiring boards 25 and standing them on a wiring board 29, and its outside is covered with a hermetic case 28 and inert gas, etc., are charged in the case 28 to protect contacts. Each unit wiring board 25 is equipped with (n) actuators 20 for decoding bar drive and connections among 2n subscriber lines 4a and 2n extensions 1a are made by n×2n actuators 20 in total in this device. The wiring board 29 has subscriber line insertion holes 29a at one terminal side and terminal insertion holes for inserting the 1st connection terminal 10 of each unit wiring board 25 on the top surface side, and a conductor is laid so that the respective subscriber lines 4a and the 1st connection terminals 10 are connected together electrically.