An electrical plug connector having a hollow cylindrical housing and having a contact sleeve in the form of a hollow cylinder having a casing wall, which contact sleeve is arranged radially inside the housing, for producing a mechanical and an electrical contact with a counterpart connector, wherein at least one contact spring tongue which can be deflected resiliently and has a free end is arranged on the casing wall of the contact sleeve and is configured in such a way that the free end projects in the radially inward direction beyond the casing wall of the contact sleeve and forms a contact surface for electrical and mechanical contacting of the counterpart connector. At least three ribs are formed on an outer periphery of the casing wall of the contact sleeve which project beyond the casing wall in a radially outward direction.