To provide a seat belt capable of providing a characteristic approximate to a desired webbing elongation characteristic.

A webbing 10 has a structure in which three layers, namely an upper layer 11, an intermediate layer 12, and a lower layer 13, are stacked in the thickness direction. The upper layer 11 is plain-woven from warps 11A, the lower layer 13 is diagonally woven from warps 12A, and the intermediate layer 12 has no weft and has warps 12A arranged in a tension state in the elongation direction of the webbing 10. The webbing 10 thus has a structure of three layers having a different warp forming method, and loosenesses of the warps constituting respective layers are different from each other. Thus, when a tensile load is charged on the webbing, the layers come into the tension states sequentially from the layer having less looseness and receive the tensile loads. Therefore, the load-elongation characteristic of the webbing 10 can be changed gradually (step by step).