Abstract: An apparatus for continuously producing a heat-shrinkable crosslinked resin tube from a crosslinkable resin is provided, comprising in successive connection, an extruder head for extruding the resin into a hollow tube, a fluid under pressure being introduced into the interior of the tube being extruded, a crosslinking cylinder disposed downstream of the head for heating the tubular resin for crosslinking, a flare die disposed downstream thereof for allowing the tube to expand under the fluid pressure, a cooling cylinder disposed downstream thereof for cooling the tube, a guide for deforming the tube into a flattened form, and rollers for pressing and drawing the tube away from the extruder head, wherein a smooth interior surface free of a substantial gap or step extends continuously from the crosslinking cylinder to the cooling cylinder.