A lumbar support belt includes a lumbar belt unit (1) and two elastic supporting units (3). The lumbar belt unit (1) has a lumbar belt body (11), two fixing portions (12) and two mounting portions (13). The lumbar belt body (11) has flexibility. The two fixing portions (12) are respectively disposed at two opposite ends of the lumbar belt body (11). The two mounting portions (13) are respectively located between the two opposite ends and the middle portion of the lumbar belt body (11). The two elastic supporting units (3) are respectively disposed on the two mounting portions (13) and can provide an upward supporting force. Each of the elastic supporting units (3) includes a supporting member (31) capable of abutting against an armpit of a user. Accordingly, the weight of the upper body of the user can be transferred to the lumbar belt unit (1) so as to provide support to the lumbar of the user.
