Cancer is the major cause of death in Japan; hence, countermeasures against cancer are conducted as a national policy. Although the development in the field of cancer chemotherapy has been significant, it is also complicated. Therefore, pharmacist intervention is essential to ensure that the patients receive safe and appropriate medication. There are multiple stages of cancer chemotherapy, and these include working out the chemotherapeutic regimen, prescribing the regimen, checking the prescription, mixing the preparation of anticancer drugs, explanation to patient, and clinical evaluation of therapy. Hence, we conducted wide-ranging studies in this field. We studied proper use of antiemetic drugs, which were administered prophylactically against chemotherapy-induced nausea and vomiting in working out the chemotherapeutic regimen, and we developed a safe and efficient method by using computer regarding prescription checking and mixing preparation of anticancer drugs. In addition, we evaluated the effectiveness of chemotherapy against standard therapy. These study results could provide us with useful knowledge regarding the development of safe cancer chemotherapy and confirm the effectiveness of therapy, and we could feed back these outcomes into the clinical setting. The results revealed that when problems are resolved because of pharmacist intervention in clinical practice, the pharmacist could support the medical examination of the physician, obtain practical results directly linked to the benefit of the patient, and contribute towards the development of safe and effective cancer chemotherapy. Since the need for pharmacists in clinical practice is increasing, our results would provide essential information regarding the contribution of pharmacists to cancer chemotherapy.