A jack connector includes a main body, contact terminals, and an engaging assembly. The main body has a lateral opening on its one side surface and a top opening on a top surface connected to the side surface. A portion of the contact terminals are provided in the main body. The engaging assembly is mounted on the top surface of the main body to surround the top opening. The engaging assembly has two engaging plates protruding from the top opening. When a plug is inserted into the jack connector via the lateral opening, the two engaging plates of the jack connector are engaged with the plug, so that the plug can be electrically connected to the jack connector via the contact terminals.