PURPOSE: To provide both side clad steel of less work hardened base material and free of thickness variations, a first clad material is explosion contacted to base material surface, a second clad material is placed in the back of the base material, and explosion contacted at right angle to the first explosion.

CONSTITUTION: Clad explosion contact to the back of base material is made at approximate right angle to the first explosion contact. For round material, a first explosion contact is made in the direction of 1, a second direction is selected at right angle direction 2 to the axis 1 and the center P, or in the range of upper and lower positions 2', 2" within 15 degree center angle. For square material, if a first explosion contact is made in the direction of 1, a second direction is selected at right angle direction 2 to the first side, any position 2, 2', 2" on the side. Prior to the second explosion contact, the first strain is corrected with reference to the material back surface and then the material is polished to be ready for the second explosion.