A high-speed transmission connector is described that includes a housing, a row of front side contacts supported on the housing, a row of rear side contacts supported on the housing, and a metal member. The housing has a slot to be fitted with a header of an external communication partner, and an upper plate portion and a lower plate portion facing each other vertically across the slot. The front side contact portions are exposed on a front side in the slot and the rear side contact portions are exposed on a rear side in the slot. The metal member supports the upper plate portion and the lower plate portion and fastens the upper plate portion and the lower plate portion.