Disclosed is a musical accessory, equipped with a tuner for stringed instruments and/or a metronome, capable of generating power by itself, which is convenient to use. In an aspect, the musical accessory comprises a casing housing a sensor, an amplifier, an A/D converter, an indication unit, a microprocessor, and a power supply unit, wherein the power supply unit includes a driver pivotably installed on one side of the casing, a power generation module for generating electromotive force by receiving rotary power from the driver, and a charger connected to the power generation module and storing some amount of the electromotive force, wherein the musical accessory is operated by receiving power from the charger. In another aspect, the musical accessory comprises a casing housing a tempo and beat selection unit, a microprocessor, and a power supply unit which are installed in the casing, wherein the power supply unit includes a driver pivotably installed on one side of the casing, a power generation module for generating electromotive force by receiving rotary power from the driver, and a charger connected to the power generation module and storing some amount of the electromotive force, wherein the musical accessory is operated by receiving power from the charger.