Method and tool for preventing sliding down of shoulder belt of shoulder bag, and shoulder bag

A shoulder belt slide-down preventing method of a shoulder bag, comprising:

• forming a ring-shape space between a belt body and a necklace element, the necklace element being in a total length of 35˜53 cm and comprising a metal chain, a cord formed by braiding a leather material or an ornament necklace made of materials selected from the group consisting of pearls, metals, natural stones and mixtures thereof, the ring-shape space being formed by connecting the necklace element to respective separate positions of the belt body of the shoulder bag, and the belt body being configured to hang on one shoulder that is at a bag side, wherein the necklace element of the ring-shape space is configured to hang around and contact a surface of a lateral side of the neck on the other shoulder while a portion of the belt body of the ring-shape space hangs on the one shoulder, thereby preventing the belt body from sliding down from the shoulder, wherein both ends of the necklace element are connected in a freely movable manner along a length direction of the belt body and are detachable from the belt body.