A friction reducing agent for seat belts which contains a polyether/polyester prepared from a polyether diol compound and an aliphatic carboxylic acid and having an average molecular weight of 2,000 to 15,000 and preferably further contains a silicone compound. The agent can be applied to raw yarns for seat belts in the yarn making step or to seat belt webbing. The seat belts treated with this agent are excellent in friction reduction before or after wearing and also in retractability thereof and wear resistance.
