Receptacle connector with latch arms and plug connector to be connected thereto

To provide a receptacle connector and a plug connector, wherein the receptacle connector has a greater force for holding the plug connector in the pull-out direction, verification of their fitting can be done easily and even if the fitting work is done blindly, incomplete fitting will not be made, and these merits can be accomplished while their thicknesses are reduced. A receptacle connector with latch arms comprising a receptacle connector body having a groove into which a plug connector is inserted, a contact provided in the receptacle connector body, and a pair of latch arms extending outward in the depth direction from two locations spaced from each other in the width direction of the receptacle connector body, the pair of latch arms being able to undergo elastic deformation in the width direction. Each latch arm is provided with a retaining part, and the retaining part is provided with a guiding part, a fixed side width fitting face and a fixed side depth fitting face.