A lumbar support belt having a transverse median axis of symmetry, and comprising: - a back pad intended to be placed against the back of a user and including two separate dorsal members (8, 9) linked by a linking member comprising at least one first and one second elastic textile strips, each strip having a medial edge which substantially coincides with the transverse median axis and which is fastened to the medial edge of the other strip, and a lateral edge fastened in the vicinity of the medial edge of the corresponding dorsal member (8, 9); - two elastic textile arms (4, 5) intended to be positioned on either side of the lower part of the trunk of the user, each of said arms (4, 5) being fastened by its medial edge to a lateral edge of a dorsal member (8, 9) and having a lateral extreme portion, the lateral extreme portions of the two arms (4, 5) being provided with complementary attachment means to be able to be assembled when they are placed one over the other facing the abdominal area of the user, the two arms (4, 5) and the back pad forming a flattened V where the lateral extreme portions of the arms (4, 5) are located above the back pad, when the belt is laid flat and in the unstressed condition; - two elastic textile straps (6, 7) located at the outer side of the belt and arranged in a V whose tip is downwardly directed, each strap (6, 7) having on the one hand a medial edge which substantially coincides with the transverse median axis and which is fastened to the medial edge of the other strap, and on the other hand a lateral edge fastened to the corresponding arm (4, 5), the two straps (6, 7) being fastened in their medial area on the medial area of the linking member, in the lower part thereof; characterized in that the two dorsal members (8, 9) of the back pad are substantially arranged in a V whose tip is downwardly directed, when the belt is laid flat and in the unstressed condition, and in that the at least first and second elastic textile strips form the two arms of a V whose tip is downwardly directed. - a back pad intended to be placed against the back of a user and including two separate dorsal members (8, 9) linked by a linking member comprising at least one first and one second elastic textile strips, each strip having a medial edge which substantially coincides with the transverse median axis and which is fastened to the medial edge of the other strip, and a lateral edge fastened in the vicinity of the medial edge of the corresponding dorsal member (8, 9); - two elastic textile arms (4, 5) intended to be positioned on either side of the lower part of the trunk of the user, each of said arms (4, 5) being fastened by its medial edge to a lateral edge of a dorsal member (8, 9) and having a lateral extreme portion, the lateral extreme portions of the two arms (4, 5) being provided with complementary attachment means to be able to be assembled when they are placed one over the other facing the abdominal area of the user, the two arms (4, 5) and the back pad forming a flattened V where the lateral extreme portions of the arms (4, 5) are located above the back pad, when the belt is laid flat and in the unstressed condition; - two elastic textile straps (6, 7) located at the outer side of the belt and arranged in a V whose tip is downwardly directed, each strap (6, 7) having on the one hand a medial edge which substantially coincides with the transverse median axis and which is fastened to the medial edge of the other strap, and on the other hand a lateral edge fastened to the corresponding arm (4, 5), the two straps (6, 7) being fastened in their medial area on the medial area of the linking member, in the lower part thereof;