An airbag device includes: an airbag having an inflow opening for introducing an inflation gas and being formed in a folded body; a bag holder attached to a peripheral edge of the inflow opening; an airbag cover attached to the bag holder; and an inflator disposed by inserting an upper side in the folded body from the inflow opening, wherein: the airbag cover has a ceiling wall that covers an upper surface remote from the inflow opening of the folded body; the folded body is equipped with a housing recess that is capable of housing a top of a main body unit of the inflator; a part around the housing recess is supported by the bag holder; and a ceiling surface of the housing recess is formed as a shape in which a clearance is provided between the top of the main body unit of the inserted inflator.