The present invention is directed to increase the resonance of an instrument by applying a conductive medium formed of a mixture of resonance increasing materials to the instrument. According to the present invention, the method for increasing the resonance of an instrument such as a woodwind instrument having a cap holder inside and a pad coupled to the cap holder comprises: an agitation step for agitating a mixture of a conductive medium that contains at least one of platinum, gold, silver, copper, nickel, bronze, brass, phosphor bronze with solid silicon; a mixture heating step for heating the agitated mixture; a coagulation step for naturally cooling the heated mixture and coagulating into a solid; a mixture pulverization step for pulverizing the mixture; a mixture application step for applying the mixture to the inside of the cap holder; and a pad attaching step for attaching a pad to the interior of the cap holder after the mixture application step.