Until now, automatic contrast agent injector syringes licensed for consecutive one-time use have been employed with a number of patients. In 2016, regulation of automatic injector syringes ensured their single use, and reuse was strictly limited by law. However, this regulation creates the social problems of rising medical costs and resource waste. Many doctors are not significantly concerned about infection from contrast agent injection because the needle and connection lines on the patient side are set up for single use, the connections between syringes and contrast agents are reusable, and there are no reports of excessive infection. However, infection can nevertheless occur with injection of contrast agents. We should therefore implement the correct and safe use of contrast agents and take precautions against infection. To prevent infection due to contrast agents, syringes and connection lines for injection of such agents should be used once per patient, or multi-use licensed products should be used. In the latter case, reverse flow prevention filters must be used on the patient's side.