An electrical receptacle connector includes a mount member, a tongue, first terminals, second terminals, and a shielding plate. The mount member and the tongue are received in a metallic shell. The terminals and the shielding plate are on the mount member and the tongue. The tongue includes terminal grooves and recesses. The terminal grooves are formed on a first surface of the tongue. Each of the recesses is recessed toward a tip of the tongue from an inner sidewall in the corresponding terminal groove. Flat contact portions of the first terminals are held in the terminal grooves. End portions of the flat contact portions are received in the recesses. Therefore, upon the tongue is deflected, the flat contact portions are constrainted in the recesses and not detached from the tongue, thereby improving stability and reliability in the contact with an electrical plug connector.