A woman in her late 50s visited our department because an abnormal shadow of her right lung was seen on her chest radiographs. She was diagnosed with Stage ⅠA primary lung adenocarcinoma with EGFR exon 19 deletion mutation by performing thoracoscopic middle lobe resection and lymph node dissection. After 1 and a half years, the lung metastasis recurred and she received gefitinib(GEF)monotherapy for 9 months and withdrew because of the sustained complete response(CR). Three years and 7 months after the first visit, she was diagnosed as having complication of revised international staging system(R-ISS)Ⅱ multiple myeloma with anemia, retinal vein occlusion, and M proteinemia. It was decided that treatment for myeloma should be given priority and hence, Bd, high dose chemotherapy with auto-peripheral blood stem cell transplantation(aPBSCT), Ld, ELd and Pd therapy were performed sequentially until progressive disease(PD)and survival benefit were evident. As lung metastasis of adenocarcinoma also progressed, myeloma treatment was terminated, GEF was administered intermittently and consequently, shrinkage of the lung metastasis was confirmed. Depending on sequential alternating chemotherapy for both malignancies, a relatively long survival time of 5.4 years from the initiation of treatment for myeloma and 7.5 years from the recurrence of lung adenocarcinoma was achieved.