A multi-cyclone dust collector including at least one first cyclone (10) forcing contaminants-laden air that is entered into a lower portion (22) of the at least one first cyclone (10) to whirl so as to centrifugally separate contaminants from the contaminants-laden air; and at least one second cyclone (60) being disposed around the at least one first cyclone (10), the at least one second cyclone (60) forcing semi-clean air that is discharged from the at least one first cyclone (10) and is entered into a lower portion of the at least one second cyclone (60) to whirl so as to centrifugally separate fine contaminants from the air.