A detecting apparatus used in a bonding apparatus including a capillary and a detection camera disposed with a certain amount of offset from the capillary and capable of detecting a press-bonded ball at a bonding portion after bonding. For a pad in which two edges of a press-bonded ball corresponding to two adjacent sides of the pad are definite, the detecting apparatus detects the respective distances between the two sides of the pad and the corresponding two edges of the press-bonded ball, and compares the detected values to determine if these values fall within previously set allowable ranges; and if the detected values are outside the allowable ranges, the amount of offset is corrected so that the press-bonded ball comes within the allowable ranges.