A cutting device includes a fixing seat, a crank axle pivotally mounted on the fixing seat by a pivot shaft, a first saw blade mounted on the pivot shaft, a second saw blade mounted on the crank axle to move therewith, a motor mounted on the crank axle, and an adjusting unit mounted between the fixing seat and the crank axle to drive the crank axle to move relative to the fixing seat. Thus, the adjusting unit is operated to drive the crank axle to pivot, so that the second saw blade mounted on the crank axle is moved downward or upward, thereby adjusting the height of the second saw blade relative to the first saw blade so as to fit workpieces of different thickness.