The present invention relates to a variable magnification device and a telescopic sight using the same, and more particularly, to a variable magnification device which is capable of easily adjusting a magnification of a telescopic sight. The variable magnification device includes: a rotation bunch which has a ring shape conforming to the circumference of a barrel of a telescopic sight and includes a bent end formed on one side of the circumference of the rotation bunch; and a rod which is connected to the bent end and is bendable in the longitudinal direction of the barrel. The magnification of the telescopic sight can be adjusted with an aiming posture maintained, thereby allowing immediate hit on a target. In addition, a leverage effect can be used to easily and finely adjust the magnification of the telescopic sight with one hand, thereby preventing distortion of an aiming posture as maximally as possible.