A curtain airbag apparatus is provided with a curtain airbag that is embedded, in a folded or rolled state, in an upper edge portion of at least one door opening and deploys into a form of a curtain, the curtain airbag having: a first deployment portion deploying downward by inflating with gas supplied from upon a side collision and rollover of the vehicle; a second deployment portion deploying downward by inflating with gas supplied at least upon a rollover of the vehicle, such that the second deployment portion is located in an area that does not overlap, as viewed laterally, an area in which the first deployment portion is located; and an internal pressure difference creator that makes an internal pressure of the second deployment portion higher than an internal pressure of the first deployment portion at least upon a rollover of the vehicle.