A connector in which the deformation of lock portions is prevented, and the connector can have a compact design, and housings are prevented from being displaced with respect to each other in both longitudinal and transverse directions. Transverse grooves of a dovetail shape are formed respectively in widthwise opposite ends of an upper surface of a lower housing at a front end portion thereof, and longitudinal grooves of a dovetail shape are formed in a widthwise central portion of this upper surface. Transverse ribs of a dovetail shape are formed respectively at widthwise opposite ends of a lower surface of an upper housing at a front end portion thereof, and longitudinal grooves of a dovetail shape are formed on a widthwise central portion of this lower surface. The transverse ribs are greater in projecting height than the longitudinal ribs. When the ribs are press-fitted respectively into the associated grooves, the two housings are locked together. When an external force of above a predetermined level is applied so as to separate the two housings from each other, the ribs are withdrawn respectively from the grooves, thereby disconnecting the two housings from each other.