A back plate of a waist support includes a supporting section and two wings. The supporting section has a valley portion for receiving a wearers spine. The two wings are symmetrically connected to the supporting section from two widthwise opposite sides thereof and each have plural lengthwise grooves, for making the wings of the back plate bendable. Thereby, the waist support is endurable and supportive and can effectively distribute the load that is focused on of the wearers lumbar vertebrae.
