A medical device includes an extracorporeal unit including a power transmitting unit that transmits electric power from outside of a living body into the living body in a non-contact manner, and a medical instrument embedded in the living body. The medical instrument includes a power receiving unit that receives the electric power transmitted from the power transmitting unit, a soft portion through which an injection needle is inserted, and a plurality of light emitting units that are provided along an outer edge of the soft portion and are each configured to emit light using the electric power received by the power receiving unit. A light amount adjusting unit that adjusts a light amount of a light-irradiated region including one or more light-irradiated portions to be projected on a body surface from the plurality of light emitting units.