A 73-year-old man presented with erythematous plaques and nodules on his trunk. He was diagnosed with multiple myeloma 2 months ago and had been treated with subcutaneous injection of Bortezomib. After 10th injection of Bortezomib on his right lower abdomen, erythematous plaques and nodules occurred at the injection site and spread gradually. Histopathologic examination showed spongiosus, mild dermal edema, and perivascular and periadnexal inflammation composed of lymphocytes and eosinophils. He was treated with systemic and topical steroid with suspicion of allergic vasculitis and resolved dramatically. He was subsequently treated with Bortezomib with systemic steroid, and the skin lesion did not recur. Bortezomib is a proteasome inhibitor which blocks the production of nuclear factor-kB mediated inflammatory cytokines. In the bone marrow, it inhibits the binding of the myeloma cells to the bone marrow stromal cells and bone marrow angiogenesis which are treatment mechanisms on multiple myeloma. Cutaenous adverse reactions(cADR) caused by Bortezomib are usually asymptomatic maculopapular rash or nodules. The mechanism by which Bortezomib causes cADR is unclear, and clinical features and histologic findings have not been clearly elucidated. Steroid might be considered as an effective treatment. It is crucial to be familiar with cutaneous side effects associated with this antineoplastic agents to assess and manage these patients properly