It is an object to provide a medical light source device capable of securing a long illumination time required to use in operations in the medical field, and the medical light source device that is worn on the body of an operator to apply light to a target portion of the medical treatment is to cause an illumination section 81 to be worn on the body of the operator with a holder 7, and is provided with an acceleration sensor 80 that detects a motion of the operator, where a control section 84 controls a supply of current from a power supply section to the illumination section 81, while controlling to reduce illuminance of the illumination section 81 or to halt the passage of current to the illumination section 81 when the acceleration sensor 80 detects acceleration of a predetermined value or more.
