PURPOSE: To provide an integrated belt type weather strip capable of being manufactured with its width modified according to the use.

CONSTITUTION: A plurality of cut out holes 28a arranged intermittently in the longitudinal direction are formed onto the core material at the parts corresponding to an intermediate leg 24 of U-shaped core 20. When the core material is formed into a shape of the core, prescribed width of weather strip is obtained by drawing and bending so as to enlarge the width of the intermediate leg. The outer layer of elastomer material is worked through extrusion on the core part before or after the forming.