A method for separating bone marrow-derived nucleated cells for bone formation, which comprises the steps of: (a) washing bone marrow, comprising the sub-steps of: storing 2-5 ml of bone marrow extracted from a patient in a washing buffer; shaking the bone-marrow washing buffer 40-50 times so as to sufficiently remove impurities or fatty components from the bone marrow, centrifuging the shaken washing buffer at 1,600 rpm for 4-5 minutes; removing the supernatant, transferring the remaining bone marrow component into another washing container, shaking the bone marrow-containing container 40-50 times, centrifuging the shaken solution at 1,600 rpm for 4-5 minutes, and removing the supernatant from the centrifuged solution; (b) lysing red blood cells in the bone marrow, comprising the sub-steps of: adding a 10-fold amount of a lysis buffer to the bone marrow; and mixing the lysis buffer with the bone marrow several times using a syringe, and standing the solution for 10-20 seconds; (c) neutralizing the bone marrow lysate, comprising the sub-steps of: mixing the bone marrow solution with the same amount of a neutralizing buffer; centrifuging said solution at 1,600 rpm for 4-5 minutes, and removing the supernatant except for the precipitated nucleated cells for bone formation; (d) purifying nucleated cells from the neutralized bone marrow, comprising the sub-steps of: mixing 4-5 ml of a maintenance buffer with the nucleated cells in a container; and centrifuging said solution at 1,600 rpm for 4-5 minutes, and removing the supernatant; and (e) mixing the nucleated cells with a maintenance buffer for bone formation. (a) washing bone marrow, comprising the sub-steps of: storing 2-5 ml of bone marrow extracted from a patient in a washing buffer; shaking the bone-marrow washing buffer 40-50 times so as to sufficiently remove impurities or fatty components from the bone marrow, centrifuging the shaken washing buffer at 1,600 rpm for 4-5 minutes; removing the supernatant, transferring the remaining bone marrow component into another washing container, shaking the bone marrow-containing container 40-50 times, centrifuging the shaken solution at 1,600 rpm for 4-5 minutes, and removing the supernatant from the centrifuged solution; storing 2-5 ml of bone marrow extracted from a patient in a washing buffer; shaking the bone-marrow washing buffer 40-50 times so as to sufficiently remove impurities or fatty components from the bone marrow, centrifuging the shaken washing buffer at 1,600 rpm for 4-5 minutes; removing the supernatant, transferring the remaining bone marrow component into another washing container, shaking the bone marrow-containing container 40-50 times, centrifuging the shaken solution at 1,600 rpm for 4-5 minutes, and removing the supernatant from the centrifuged solution; (b) lysing red blood cells in the bone marrow, comprising the sub-steps of: adding a 10-fold amount of a lysis buffer to the bone marrow; and mixing the lysis buffer with the bone marrow several times using a syringe, and standing the solution for 10-20 seconds; adding a 10-fold amount of a lysis buffer to the bone marrow; and mixing the lysis buffer with the bone marrow several times using a syringe, and standing the solution for 10-20 seconds; (c) neutralizing the bone marrow lysate, comprising the sub-steps of: mixing the bone marrow solution with the same amount of a neutralizing buffer; centrifuging said solution at 1,600 rpm for 4-5 minutes, and removing the supernatant except for the precipitated nucleated cells for bone formation; mixing the bone marrow solution with the same amount of a neutralizing buffer; centrifuging said solution at 1,600 rpm for 4-5 minutes, and removing the supernatant except for the precipitated nucleated cells for bone formation; (d) purifying nucleated cells from the neutralized bone marrow, comprising the sub-steps of: mixing 4-5 ml of a maintenance buffer with the nucleated cells in a container; and centrifuging said solution at 1,600 rpm for 4-5 minutes, and removing the supernatant; and mixing 4-5 ml of a maintenance buffer with the nucleated cells in a container; and centrifuging said solution at 1,600 rpm for 4-5 minutes, and removing the supernatant; and (e) mixing the nucleated cells with a maintenance buffer for bone formation.