A matrix-switch-board unit has two wiring-pattern arrays which are respectively formed in opposite sides of the unit so as to be electrically isolated from and to cross each other, respective through holes extending between and through the crossing portions of the wiring pattern arrays on the opposite sides of the unit. A connection pin inserting and extracting device automatically and selectively inserts a connection pin into a selected one of the through holes for interconnecting the corresponding opposed, crossing pattern portions and extracts a connection pin from a corresponding one of the through holes for disconnecting same. Pivotally mounted toggle arms of the device have respective ends with laterally extending hook portions in opposed relationship and are rotatable in a first sense to engage a pin between the hook portions and in an opposite sense to release a connection pin engaged thereby.