A quick-release device for screwdriver bits, comprising: a shank having a first end and a second end, the shank having a polygonal hole longitudinally defined in the first end thereof and adapted for partially receiving a bit, wherein the bit has a groove annularly defined therein, at least one slot longitudinally defined in the first end of the shank, an annular groove defined in an inner periphery of polygonal hole and communicating with the at least one slot, an expandable limit element received in the annular groove, wherein the limit element has an outer diameter slightly smaller than a diameter of the annular groove; a tapered section annularly on an inner periphery of the annular groove toward the first end of the shank, wherein the limit element is moved with the bit when the bit is freely reversely pulled and the limit element is inwardly pushed to more tightly engage into the groove due to the tapered section such that the bit cannot be freely removing from the polygonal hole in the shank; a sleeve movably sleeved on the first end of the shank, the sleeve having at least one protrusion inwardly extending therefrom, wherein the at least one protrusion is engaged into the at least one slot to prevent the sleeve from being rotated relative to the shank, the at least one protrusion abutting against the limit element when removing the bit form the polygonal hole; a hollow stub extending longitudinally from the first end of the shank, wherein the at least one slot is longitudinally defined in the hollow stub; and a stopper secured on the first end of the hollow stub for preventing the sleeve from removing from the shank, wherein the stopper surrounds the first end of the hollow stub and the at least one slot of the hollow stub. a shank having a first end and a second end, the shank having a polygonal hole longitudinally defined in the first end thereof and adapted for partially receiving a bit, wherein the bit has a groove annularly defined therein, at least one slot longitudinally defined in the first end of the shank, an annular groove defined in an inner periphery of polygonal hole and communicating with the at least one slot, an expandable limit element received in the annular groove, wherein the limit element has an outer diameter slightly smaller than a diameter of the annular groove; a tapered section annularly on an inner periphery of the annular groove toward the first end of the shank, wherein the limit element is moved with the bit when the bit is freely reversely pulled and the limit element is inwardly pushed to more tightly engage into the groove due to the tapered section such that the bit cannot be freely removing from the polygonal hole in the shank; a sleeve movably sleeved on the first end of the shank, the sleeve having at least one protrusion inwardly extending therefrom, wherein the at least one protrusion is engaged into the at least one slot to prevent the sleeve from being rotated relative to the shank, the at least one protrusion abutting against the limit element when removing the bit form the polygonal hole; a hollow stub extending longitudinally from the first end of the shank, wherein the at least one slot is longitudinally defined in the hollow stub; and a stopper secured on the first end of the hollow stub for preventing the sleeve from removing from the shank, wherein the stopper surrounds the first end of the hollow stub and the at least one slot of the hollow stub.