What is a Medical Device?
Under the PMD Act, a medical device is defined in Article 2, Paragraph 4 as instruments, machines, appliances, or materials intended for use in the diagnosis, treatment, or prevention of disease in humans or animals, or intended to affect the structure or function of the body of humans or animals, as designated by Cabinet Order.
The phrase "designated by Cabinet Order" is important: a product does not become a medical device simply because it meets the general description. It must also fall within the categories listed in the Cabinet Order on medical device classifications.
PMD Act Article 2, Paragraph 4 — current text available at e-Gov Law Search (Japanese) and PMDA English translations.
Key elements of the definition
Intended use is central. The same physical product may or may not be a medical device depending on its intended use. A standard pressure cuff used in a hospital is a medical device; the identical product marketed for non-medical monitoring may not be.
"Designated by Cabinet Order." The Cabinet Order on Medical Devices lists the specific categories of devices subject to PMD Act regulation. If a product type is not listed, it is not regulated as a medical device even if it fits the general description in Article 2.
Animals and humans. Unlike the EU MDR, the PMD Act definition explicitly includes devices intended for veterinary use. Devices exclusively for veterinary use are regulated under the same statute but with some differences in application requirements.
In vitro diagnostics (IVDs)
IVDs are defined separately in Article 2, Paragraph 5 of the PMD Act as instruments, machines, appliances, or materials intended to be used for the diagnosis of disease in humans or animals by testing collected specimens, as designated by Cabinet Order.
IVDs follow the same three-pathway structure (Shonin / Ninsho / Todokede) as other medical devices, but have IVD-specific classification criteria and technical requirements.
Software and SaMD
The 2014 amendments to the PMD Act introduced the concept of Programme Medical Devices (プログラム医療機器) — software that is itself a medical device. This was further clarified by subsequent MHLW notifications. Software that meets the medical device definition (intended use, effect on structure/function, listed in Cabinet Order) is regulated as a medical device and must follow the appropriate pre-market pathway.
Standalone apps and AI-based diagnostic software are the most common examples requiring evaluation under this framework.
Accessories
Accessories to medical devices can themselves be medical devices if they are intended specifically for use with a regulated device and their use affects safety or performance. The MAH should confirm the classification status of accessories separately from the primary device.