Plug-in connector, which has a main body, a sliding element and latching means for secure latching to a mating plug-in connector, wherein the main body has a plug-in side and a connection side, wherein the plug-in connector forms a plug-in axis which extends through the plug-in connector from the plug-in side to the connection side, wherein the sliding element comprises the main body and is arranged thereon so as to be movable along the plug-in axis in order, owing to its displacement in the direction of the plug-in side, to act on the latching means of the plug-in connector and to release the latching between the plug-in connector and the mating plug-in connector in this way, wherein the plug-in connector has a securing element in order to block the displacement of the sliding element from a plug-inside end position to a connection-side end position when it is in the locked position, and to secure the plug-in connector against inadvertent unlocking in this way, wherein the securing element is arranged between the sliding element and the connection side of the plug-in connector, and wherein the securing element is arranged on the main body so as to be movable between an open position and a locked position, wherein the securing element can be latched to the main body both in the open and in the locked position, wherein the securing element is arranged on the plug-in connector so as to be rotatable about the plug-in axis, wherein the securing element is of annular form and surrounds the main body, wherein the securing element has at least one blocking region, characterized in that the at least one blocking region extends away from the securing element radially from the plug-in axis, and in that, after the securing element has been positioned, the blocking region is situated in the movement path of the sliding element or clears said movement path. wherein the main body has a plug-in side and a connection side, wherein the plug-in connector forms a plug-in axis which extends through the plug-in connector from the plug-in side to the connection side, wherein the sliding element comprises the main body and is arranged thereon so as to be movable along the plug-in axis in order, owing to its displacement in the direction of the plug-in side, to act on the latching means of the plug-in connector and to release the latching between the plug-in connector and the mating plug-in connector in this way, wherein the plug-in connector has a securing element in order to block the displacement of the sliding element from a plug-inside end position to a connection-side end position when it is in the locked position, and to secure the plug-in connector against inadvertent unlocking in this way, wherein the securing element is arranged between the sliding element and the connection side of the plug-in connector, and wherein the securing element is arranged on the main body so as to be movable between an open position and a locked position, wherein the securing element can be latched to the main body both in the open and in the locked position, wherein the securing element is arranged on the plug-in connector so as to be rotatable about the plug-in axis, wherein the securing element is of annular form and surrounds the main body, wherein the securing element has at least one blocking region, characterized in that the at least one blocking region extends away from the securing element radially from the plug-in axis, and in that, after the securing element has been positioned, the blocking region is situated in the movement path of the sliding element or clears said movement path.