A shaped rubber body with improved uniformity in terms of weight and/or physical properties is produced by extruding a rubber strip by a positive displacement extruding system that includes, as seen from an upstream side of the rubber strip, a screw extruder unit, a gear pump unit and an extrusion head unit with an extrusion nozzle, which are connected in series with each other. The rubber strip is fed to a rotating support along a substantially straight passage extending from the screw extruder unit to the extrusion nozzle of the extrusion head unit, passed through a gap defined between a pair of pressure roll, and applied onto an outer surface of the support by one of the pressure rolls.