Pustulotic arthro-osteitis (PAO) is a rare inflammatory osteitis of the sternoclavicular joint and palmoplantar pustulosis without acne. Although PAO regarded as a variant of SAPHO syndrome, PAO does not have acnes which are the most characteristic skin manifestations of SAPHO syndrome. Cyclosporine and DMARDs are commonly used for the treatment of PAO, but TNF-α inhibitors are a good treatment option in a few cases resistant to conventional treatments. Here, we report a case of refractory PAO treated with a TNF-α inhibitor. A 45-year-old man presented with a 3-month history of the pustulosis on the palms and shins and a 5-year history of intermittent back and sternal joint pain. Physical examination showed multiple erythematous papulopustular lesions and hyperkeratotic plaques on both palms, back and left shin. Sternoclavicular joint swelling and tenderness were accompanied. Histopathology of the skin showed intraepidermal pustules filled with neutrophils on the palm and mild acanthosis with focal parakeratosis on the back. An examination by technetium-99m bone scintigraphy revealed increased uptake in the bilateral sternoclavicular and other axial joints. Based on these findings, we made the diagnosis of PAO. Six-month treatment of oral steroid and cyclosporine showed partial improvement, so etanercept was added. Remarkable improvement of skin lesion and joint pain was achieved after 3 months of etanercept therapy.