A micro gas generator is a device that acts to retract the seatbelt (seatbelt pretensioner) in the event of a collision. The retraction of the seatbelt fixes the body to the ideal position in relation to the inflated airbag. This increases the effectiveness of the airbag, maximizing the safety for the passenger.

As a safety device during an accident, it has begun to be used for various purposes, such as the shifting of the headrests or seats, or a system where the front hood is popped up to protect pedestrians.