PURPOSE: To produce a titled material having excellent joining and dimensional shapes of a flat square wire-shaped solder material and a belt-like base material consisting of copper (alloy) by letting off the solder material on the base material along the longitudinal direction of the base material and press welding the two materials under the reduction applied by rolling rolls.

CONSTITUTION: A belt-like base material 1 consisting of copper or a copper alloy is delivered from a delivery device 4 and is degreased and descaled in a pretreating device 5. On the other hand, a flat square wire-shaped solder material 2 delivered from a delivery device 6 is passed through a similar pretreating device 7 and is placed on one side of the material 1. Both materials in this state are fed between rolling rolls 8 and 9. The material 1 and the material 2 are cold rolled and press welded under the 0W50% reduction applied on the material 1 by the rolls 8, 9 to form an inlay clad material. The clad material is passed through a heat treating device 11 according to need and is coiled on a coiler 10.