The development of drugs and medical devices is necessary for medical progress; however, safety measures need to be put in place to protect the health of the population. In order to ensure the safety of drugs and medical devices, it is important to determine measures for appropriate management of risks at any time during the development phase, the regulatory review and the post-marketing phase. Adverse events detected in clinical trials are limited due to the restricted numbers of patients enrolled in the trials. Therefore, it is almost impossible to predict rare serious adverse events during the post-marketing phase. The revised Pharmaceutical Affairs Act was established in Japan in November 20, 2013. The new act focuses on increased safety of drugs and medical devices. The Pharmaceuticals and Medical Devices Agency (PMDA) is the regulatory authority in Japan that promotes safety measures from the development phase through to the post-marketing phase. In the post-marketing phase, the PMDA collects information from the medical product companies and healthcare professionals, as well as instructing and advising them with regard to post-marketing safety measures for each drug and medical device. Since Japan has a national health insurance system, a new drug or a medical device is available throughout the country when the drug price or medical fee is listed in the National Health Insurance price list. Healthcare professionals in medical institutions must learn about the drugs and medical devices they handle, and should make an effort to maintain patient safety. The PMDA medi-navi is a very useful electronic mail delivery service that provides critical information for protecting patients from health hazards caused by adverse events. The 'risk management plan' is also important as it contains important information about safety profile and post-marketing measures of a new drug.