A buoyancy generator for a vehicle may include a housing detachably mounted on a vehicle, a buoyancy generating unit mounted in the housing and including a tube configured to be inflated and deployed to an outside of the housing and a gas supply connected to the tube and configured to supply inflation gas to the tube during operation, and a handle unit provided in the housing and having a handle to be operated to deploy the tube so that the tube floats to a water surface due to buoyancy of the tube to allow an occupant gripping the handle to float to the water surface together with the tube.