To prevent the occurrence of the connection defect of a bridge and the like by relatively moving a semiconductor chip based on the result of computation in a moving-amount computing process, transferring a conductive bonding material to a bump electrode, overlapping the semiconductor chip on the electrode pad of a substrate, and thereby facing the semiconductor chip to the substrate.

The position in the direction Z, for which the virtual reference position of a semiconductor chip 1 held by a bonding head 16 is the original position, is detected by a laser displacement gage 24. Furthermore, the position in the direction Z, for which the virtual reference position of the liquid level of a conductive bonding material 17 is the original point, is detected by a laser displacement gage 23. Based on the results of these detections, the relative descending amount of the semiconductor chip 1 is computed by a descending- amount control means 7a. The semiconductor chip 1 is relatively lowered based on the result of the computation, and the conductive bonding material 17 is transferred to the bump electrode of the semiconductor chip 1. The semiconductor chip 1, on which the conductive bonding material 17 is transferred, is overlapped on the electrode pad of the substrate.