An airbag-releasing structure capable of smoothly releasing an airbag in the vehicle, an inner case, and an airbag device are provided. In one form, the inner case of the present invention includes the inner panels connected to the inside of the outer panel, and the side walls defining the space for housing the retainer. Each inner panel includes the supporting portion connected to the fixing portion of the outer panel, the flap portion welded to the door portion, and the hinge portion formed between the supporting portion and the flap portion. The hinge portion has the apex section, the connecting section adjacent to the supporting portion, which connects the supporting portion and the apex section, and the connecting section adjacent to the flap portion, which connects the flap portion and the apex section. The connecting section adjacent to the supporting portion and the connecting section adjacent to the flap portion each have a straight section extending in the direction in which the airbag is released.