A restraining device for an occupant (0) seated in a vehicle seat including a carrier (20) extending over the lap of the seated occupant (0) when the restraining device is in use, an airbag (32) having an airbag main body (40) enclosing a main gas space and extending from a lower end (40a) to an upper end (40b) being located above the lower end (40a) when the airbag main body (40) is in its deployed state, and an inflating device for filling the main gas space. The airbag main body (40) is connected to the carrier (20) via a connection section at the lower end (40a) of the airbag main body (40) and has an impact wall (42). In order to be independent of a support from another part of the vehicle the airbag main body (40) tapers from its lower end (40a) to its upper end (40b).