PURPOSE: To easily obtain a shock-absorbing belt for improving the initial constraint of the driver, etc., with a seat belt device to constrain and protect the driver, etc., in the collision of a car, etc., and capable of lessening the shock by the absorption of the collision energy.

CONSTITUTION: An additional constituent material 15 composed of plural low- elongation high-tenacity yarns is inserted along the longitudinal direction of a warp 13 which is a principal constituent material 1 for a belt 11. The additional constituent material 15 is clamped between the upper and lower wefts 14, 14 successively woven in the longitudinal direction of the warp 13. The additional constituent material is randomly broken in the longitudinal direction when an impact load is applied to the belt. The harm index (HIC) can be decreased and the safety can be improved by the use of the belt.