Abstract: A roof airbag for a vehicle including deployment guides configured to extend in forward and backward directions of a vehicle and disposed to be spaced laterally apart from each other, an inflator located between the deployment guides spaced apart from each other and configured to discharge gas therefrom during operation thereof, and a cushion located between the deployment guides spaced apart from each other, deployed in an extension direction of the deployment guides and including a deployment chamber configured to be deployed while the gas discharged from the inflator flows thereinto and delay chambers configured such that the gas flows thereinto in a deployed state thereof.