A passenger seat airbag apparatus includes: an airbag which is housed in a folded state inside an instrument panel, and which inflates toward a passenger with a supply of gas during a frontal collision of a vehicle, and which has a vent hole that can be opened and closed; a tether whose first end is linked to a periphery of the vent hole in the airbag, and which closes the vent hole due to tension that is caused when the airbag inflates; an actuator which has a first hole that a second end of the tether is passed through, and which discontinues a linked state of the tether by cutting the tether if a predetermined condition is satisfied; and a protective member that is attached to the actuator so as to cover at least an edge portion of the first hole, and that is interposed between the edge portion and the tether.