A cover for an airbag device, which includes: a cover portion configured to cover an airbag in a folded state; a hollow insertion portion configured to be inserted into an attachment hole on the vehicle; a locking portion inserted into the attachment hole together with the insertion portion and locked at the vehicle; and a connecting portion provided inside the insertion portion and connecting inner surfaces of the insertion portion with each other so as to reinforce the insertion portion. The cover portion, the insertion portion, the locking portion, and the connecting portion are integrally formed, and the connecting portion is present at least at a position closer to a distal end side of the insertion portion in an insertion direction than the position of the attachment hole when the locking portion is locked.