A smart belt and a control method thereof are provided, in which a belt device is provided, including a strap portion comprising a plurality of magnet patterns, a first sensor portion configured to sense one of the plurality of magnet patterns while the strap portion is being fastened to a buckle portion, and a controller configured to obtain a length of a waist circumference of a user that corresponds to the magnet pattern sensed by the first sensor portion. The belt apparatus may additionally include a clip portion connecting the strap portion with the buckle portion, and a second sensor portion configured to measure a tension exerted on the clip portion while the strap portion is being fastened to the buckle portion. The controller may correct the length of the waist circumference using a waist circumference correction value corresponding to the measured tension.
