Helical belt and belt transmission gear

A passenger protection device capable of protecting a passenger sitting on a front seat and moving obliquely forward and toward a vehicle exterior-side upon an oblique collision or offset collision of a vehicle, the passenger protection device comprising:

• a front airbag accommodated with being folded in front of the front seat and configured to inflate so as to cover a front of an upper half body of the passenger sitting on the front seat by allowing an inflation gas to flow therein upon activation;
• a front inflator configured to supply the inflation gas to the front airbag upon activation;
• an airbag for window accommodated with being folded at an upper edge-side of a window arranged at a lateral side of the passenger and configured to inflate so as to cover a vehicle interior-side of the window by allowing an inflation gas to flow therein upon activation;
• and
• an inflator for window configured to supply the inflation gas to the airbag for window upon activation, wherein
• the airbag for window includes a bag-adjacent inflation part configured to cover a side of a head of the passenger received by the front airbag upon deployment, and
• an activation start timing of the inflator for window is set within a range of −20 ms to −5 ms from a time at which the front airbag having completely inflated starts to receive the passenger.