A semiconductor device includes a wiring pattern formed on a board, and a semiconductor chip bonded to the wiring pattern by ultrasonic welding. The wiring pattern is formed such that when the semiconductor chip is disposed on the wiring pattern, a range shared between the wiring pattern and positional variation regions of portions to be bonded of the semiconductor chip accompanied by the ultrasonic welding becomes as wide as possible. Such a semiconductor device makes it possible to ensure a sufficient positional deviation range of a wiring pattern with respect to a positional deviation in each bump type electrode, and hence to cope with a multipin structure for flip-chip mounting and to improve both an initial bonding characteristic and a mounting reliability.