A technique is provided effective in improving rider retraining performance of an airbag in a motorcycle airbag system to be mounted to a motorcycle. In one form, an airbag system to be mounted to a motorcycle is constructed such that the way of folding the airbag is devised to set the fold release resistance of the rider-side airbag part lower than that of the other part of the airbag in the early stage of the airbag deployment.
