A length adjustment device comprising: a handle including a push button; a main pole coupled to the handle; an expansion pole retracted/extracted into/from the main pole; and a length adjustment means enabling the expansion pole to be retracted/extracted into/from the main pole through manipulation of the push button, thereby adjusting the entire length, wherein the length adjustment means includes: a weight transfer means (610, 620) installed at the inside of the main pole, the weight transfer means (610, 620) transferring a weight of the push button; a spin pipe assembly fixedly installed at the inside of the expansion pole; wherein the spin pipe assembly includes: a spin cover pipe fixedly installed at the inside of the expansion pole; and a plurality of spin pipes accommodated in the spin cover pipe, the plurality of spin pipes having round-shaped grooves machined at a constant pitch at an inner circumferential surface thereof, and wherein the plurality of spin pipes are configured as a long spin pipe which is relatively long, a plurality of short spin pipes which are relatively short compared to the long spin pipe, and a last spin pipe which is similar to the short spin pipe, and are inserted into the spin cover pipe through one end portion of the spin cover pipe in a sequence of the long spin pipe, the short spin pipes, and the last spin pipe; and a clamp assembly installed throughout a boundary between the main pole and the expansion pole, the clamp assembly allowing the spin pipe assembly to maintain a lock state or an unlock state by pressurizing the spin pipe assembly to the outside or by releasing the pressurization. a handle including a push button; a main pole coupled to the handle; an expansion pole retracted/extracted into/from the main pole; and a length adjustment means enabling the expansion pole to be retracted/extracted into/from the main pole through manipulation of the push button, thereby adjusting the entire length, wherein the length adjustment means includes: a weight transfer means (610, 620) installed at the inside of the main pole, the weight transfer means (610, 620) transferring a weight of the push button; a spin pipe assembly fixedly installed at the inside of the expansion pole; wherein the spin pipe assembly includes: a spin cover pipe fixedly installed at the inside of the expansion pole; and a plurality of spin pipes accommodated in the spin cover pipe, the plurality of spin pipes having round-shaped grooves machined at a constant pitch at an inner circumferential surface thereof, and wherein the plurality of spin pipes are configured as a long spin pipe which is relatively long, a plurality of short spin pipes which are relatively short compared to the long spin pipe, and a last spin pipe which is similar to the short spin pipe, and are inserted into the spin cover pipe through one end portion of the spin cover pipe in a sequence of the long spin pipe, the short spin pipes, and the last spin pipe; and a clamp assembly installed throughout a boundary between the main pole and the expansion pole, the clamp assembly allowing the spin pipe assembly to maintain a lock state or an unlock state by pressurizing the spin pipe assembly to the outside or by releasing the pressurization. a weight transfer means (610, 620) installed at the inside of the main pole, the weight transfer means (610, 620) transferring a weight of the push button; a spin pipe assembly fixedly installed at the inside of the expansion pole; wherein the spin pipe assembly includes: a spin cover pipe fixedly installed at the inside of the expansion pole; and a plurality of spin pipes accommodated in the spin cover pipe, the plurality of spin pipes having round-shaped grooves machined at a constant pitch at an inner circumferential surface thereof, and wherein the plurality of spin pipes are configured as a long spin pipe which is relatively long, a plurality of short spin pipes which are relatively short compared to the long spin pipe, and a last spin pipe which is similar to the short spin pipe, and are inserted into the spin cover pipe through one end portion of the spin cover pipe in a sequence of the long spin pipe, the short spin pipes, and the last spin pipe; and a clamp assembly installed throughout a boundary between the main pole and the expansion pole, the clamp assembly allowing the spin pipe assembly to maintain a lock state or an unlock state by pressurizing the spin pipe assembly to the outside or by releasing the pressurization. a spin cover pipe fixedly installed at the inside of the expansion pole; and a plurality of spin pipes accommodated in the spin cover pipe, the plurality of spin pipes having round-shaped grooves machined at a constant pitch at an inner circumferential surface thereof, and wherein the plurality of spin pipes are configured as a long spin pipe which is relatively long, a plurality of short spin pipes which are relatively short compared to the long spin pipe, and a last spin pipe which is similar to the short spin pipe, and are inserted into the spin cover pipe through one end portion of the spin cover pipe in a sequence of the long spin pipe, the short spin pipes, and the last spin pipe; and a clamp assembly installed throughout a boundary between the main pole and the expansion pole, the clamp assembly allowing the spin pipe assembly to maintain a lock state or an unlock state by pressurizing the spin pipe assembly to the outside or by releasing the pressurization.