In coupling a male connector containing plural male terminals with a female connector containing plural female terminals, the conventional coupling method wherein the coupling is maintained principally by the frictional coupling force between said male and female termianls is unable to provide sufficiently high coupling strength and may give rise to loose coupling or complete decoupling of the connectors when the connecting wire is subjected to a tensile force or the connectors are subjected to an external force or a shock. Also when the female connector is fitted into the male connector, the lack of means for effectively defining the fitting position may lead to erroneous connections resulting from incorrect positioning. Furthermore, the conventional connectors, wherein the coupling force between the male and female terminals is made as high as possible in order to ensure satisfactorily strong coupling between the male and female connectors, have generally very poor detachability and are very difficult to disconnect manually.