Lumbar corset (10) comprising two permanently joined half-parts (12, 14) joined, at the respective distal ends (16, 18), by means of a joining element (20). The respective proximal ends of the two half-parts are configured to overlap each other and be joined in the closed configuration of the corset. The corset is provided with a closing system constituted by a set of first and second dorsal straps (26, 32), each of which extending between the distal end of a corresponding second and first half-part, respectively, and first and second free pulleys (38, 40). First and second primary side straps (42, 46) are operatively connected to the corresponding dorsal straps by interposing first and second secondary side straps (60, 66) and first and second mobile pulleys (58, 64).