Proposed is a roof airbag that is disposed at the roof of a vehicle and is deployed into an interior space of the vehicle. A bracket is provided to the roof. An inflator is connected to the bracket and configured to discharge an inflation gas when operated. An airbag cushion is provided to an airbag cover connected to the bracket in a foldable way and deployed into an interior space of the vehicle by the inflation gas supplied by the inflator. A tether is configured such that one end thereof is fixed to the roof side, and the other end of which is connected to the airbag cushion. The tether supports the airbag cushion so that, when the airbag cushion is deployed, the airbag cushion is deployed toward a seat.