An airbag constructing technology is provided that is useful for improving the protection of a driver upon the occurrence of a vehicle accident, and related techniques. The airbag apparatus to be mounted on an automotive two-wheeler has an airbag which is inflated in a driver-protecting area formed in front of the driver upon the occurrence of a front vehicle collision. This airbag has a tether connecting inner wall surfaces facing each other of the airbag. Inflation of the vehicle rear side wall of the airbag toward the driver is regulated via the tether. Inflation of the vehicle front side wall of the airbag toward the front vehicle is allowed. This tether is prepared by sewing first to third tether component pieces to each other sewn to the inner wall surface of the airbag.