PURPOSE: To perform micro-displacement of a means for deforming controllably the shape of an extrusion molded product in the free directions in an extrusion molding device and dispose and remove the device easily.

CONSTITUTION: An extrusion molding device 1 consists of an extrusion molding machine 3 provided with an extrusion mold 15 for extruding heat molten synthetic resin into a continuous molded product of constant transverse section, a shaping component 5 for shaping a molded product 21 extruded out of the extrusion mold 15, a shaping component drive mechanism 7 retaining the shaping component 5, not being in the state of connecting mechanically with the extrusion molding machine 3 and with its mechanical origin disposed to retain the given positioning relation with the extrusion molding machine 3, a sensing means 9 for sensing the extrusion length of a molded product extruded out of the extruder 15 and a control device 11 for controlling the shaping component 5 of the shaping component drive mechanism 7 to move close to or separate away to an orifice 17 of the extrusion mold 15 correspondingly to the sensing result of said sensing means 9.