Abstract: A locking device for connectors of printed wired boards, the connectors being of EURODIN (DIN41612C/R) type, which device prevents the disconnection of two coupled connectors, consisting of a rectangular elongated plate in plastic material having four tenons at its corners in relief over said plate, the tenons inserting in end recesses of the connectors when the plate is overlapped to two coupled connectors, the plate further having two resilient end arms, perpendicular to the plate and extending in the same direction as the tenons, each arm having a locking tooth which hooks to the lower side of the connector pair when the plate is overlapped to the coupled connector pair.