A back plate of a waist support includes a plate body and two spring members. The plate body has a valley portion and two positioning holes. The two positioning holes are arranged symmetrically on the right and left sides of the valley portion. Each of the spring members is installed in the positioning hole of the plate body and provides a propping force to a wearer of the waist support. Thereby, the waist support can more effectively distribute the load that is otherwise focused on of the wearers waist vertebra and in turn provides the wearer with more comfort.
