An electrical coaxial connector comprising a signal-joining contacting conductor and a grounding contacting conductor each supported by an insulating base member, wherein a body portion of the signal-joining contacting conductor has a press-contacting part with a contacting protrusion for contacting with a signal-joining conductor in a mating connector and a first base part in such a manner that a measure of thickness of the press-contacting part including the contacting protrusion is not more than the maximum measure of thickness of the first base part, and an annular portion of the grounding contacting conductor has an engaging part with an engaging protrusion for engaging with a grounding conductor in the mating connector and a second base part in such a manner that a measure of thickness of the engaging part including the engaging protrusion is not more than to the maximum measure of thickness of the second base part.