A 25-year-old man was admitted to our hospital with gait disturbance and muscle pain in both lower legs, which gradually progressed in two weeks. A chest computed tomography scan revealed no abnormal lung opacities, but mediastinal lymphadenopathy was present. Using a specimen obtained by endobronchial ultrasound-guided transbronchial needle aspiration, we performed a PCR to check for Mycobacterium tuberculosis. The result was positive, and he was diagnosed with mediastinal lymph node tuberculosis. Pathological findings of the muscle were not indicative of myositis or vasculitis and revealed no lesion of caseating granulomas. A nerve conduction study showed axonal involvement of the lower limbs. Subsequently, a combined antituberculous and steroid pulse treatment was initiated. Patient symptoms and mediastinal lymphadenopathy improved significantly, and he eventually became ambulatory. The M. tuberculosis infection was suggested to have triggered the immune-mediated peripheral neuropathy.