PURPOSE: To form bumps simply, with good accuracy and at fine pitches by a method wherein each bump is formed of a metal ball fixed on a recessed part in a circuit.

CONSTITUTION: A bump 5 is formed of a metal ball 15 fixed on a recessed part 19 in a circuit 3 with a solder layer 7 or a conductive bonding agent. The recessed part 19 is a hole provided in the circuit pattern 2 by etching or a hole provided in an insulating layer for covering the circuit pattern 3 or is formed by punching out mechanically or recessing a conductor, on which the circuit 3 is formed. By this constitution, with the bump 5 formed by a simple process and a simple treatment, the recessed part 19 is formed with high position al accuracy in the pattern 3. Accordingly, it becomes possible to form the bump 5 with high positional accuracy.