We have experienced two cases of proximal neurogenic muscular atrophy with low back pain. A 56-year-old woman visited our hospital for low back pain and muscle weakness of lower extrimities. After various investigations, we made a diagnosis of Vulpian-Bernhardt type SPMA.A 26-year-old man has been followed up as Kugerberg-Welandar disease. Recently he has begun to complain of low back pain.In two cases, lumbar lordosis is increased due to muscle weakness of limb girdle muscles. No organic changes are revealed in their lumbar spines. It is suggested that their low back pain is caused by malposture or increased lumbar lordosis. Application of corset was effective for their treatment.