1.  Field of the Invention
This invention relates to an automotive seat belt system for a vehicle and a seat belt retractor device for the seat belt system. 
2.  Description of the Prior Art
Conventionally, a seat belt is passed through a seat belt guide provided on an upper portion of the center pillar of the vehicle body and is connected to a seat belt retractor device fixed to the vehicle body at the lower end of the center pillar.  With such an arrangement, the angle by which the seat belt is bent at the seat belt guide is inherently small, and accordingly relatively heavy load acts on the seat belt guide for a given load acting on the seat belt upon collision.  In order to withstand heavy load, the seat belt guide mounting portion must have a sufficient rigidity. 
In a four-door pillarless hardtop, the seat belt guide is fixed to the roof of the vehicle body and accordingly, the seat belt extends vertically across the side window to dispel open feeling which is particularly expected of the pillarless hardtop.  When the seat belt guide is mounted on the seat back in order to avoid this problem with the seat belt retractor device being fixed to the vehicle at the lower end of the center pillar, heavy load acts on the seat belt guide as described above and accordingly, in order to ensure performance of the seat belt in this case together with sufficient rigidity of the seat belt guide mounting portion, the size and the weight of the seat must be large.