 It will be essential to obtain the Korean clinical data about the efficacy and safety of the re-treatment with bortezomib as well as to analyze its actual pattern. The current trial is a prospective, multi-center, Phase 4, observational study that will be conducted to collect such demographic data as a past history, a previous history of drug use, the degree of responses to initial treatment, the frequency of previous therapies, age, Eastern Cooperative Oncology Group ECOG performance status, the concomitant drugs that are used for re-treatment and the pattern of treatment for patients with multiple myeloma and who were re-treated with injectable bortezomib. Also safety data will be collected. Observational Study -No investigational drug administered 