A therapeutic agent for myeloma comprising a combined use of a nitrogen mustard anticancer agent and anti-IL-6 receptor antibody. Thus, a therapeutic agent for myeloma comprising anti-IL-6 receptor antibody for use in combination with a nitrogen mustard anticancer agent; a therapeutic agent for myeloma comprising a nitrogen mustard anticancer agent for use in combination with anti-IL-6 receptor antibody; and a therapeutic agent for myeloma comprising a nitrogen mustard anticancer agent and anti-IL-6 receptor antibody.