An implant for a living body is designed so that the drug release level can be adjusted to make it possible to perform treatment corresponding to the severity of disease state and the effectiveness of the drug on each individual. The implant includes a drug, and is inserted into a target part of a living body to effect sustained release of the drug, the implant including a photoactive agent that accelerates the release of the drug when irradiated with laser light. The implant is inserted into a living body, and laser light is appropriately applied to the implant to adjust the release level of the drug released into the living body. An eye disease or the like is treated using the above method.
