An actuator according to various embodiments of the present invention comprises: a stator including a bracket, a yoke located on the bracket, and a coil for encompassing the circumference of the yoke; a permanent magnet encompassing the circumference of the coil; a vibrator including a weight encompassing the circumference of the permanent magnet, and a plate for supporting the permanent magnet and the weight; an elastic member located between the bracket and the vibrator so as to support the vibrator; and a magnetic fluid which is located between the vibrator and the stator, and which provides damping stability when the vibrator vibrates, wherein the weight of the magnetic fluid can be between 0.24% to 0.71% on the basis of the weight of the vibrator. Other various embodiments are possible.