The present disclosure discloses a dust collector for a vacuum cleaner, including a first cyclone disposed within an outer case to filter out dust from air introduced from an outside thereof and introduce the air from which dust has been filtered out to an inside thereof, a second cyclone accommodated in the inside of the first cyclone to separate fine dust from the air introduced to the inside of the first cyclone, a first guide vane spirally extended from an annular shaped first space between the first and the second cyclone to induce rotational flow so as to introduce air introduced into the first space to an inlet of the second cyclone, and a second guide vane spirally extended along an inner circumference of the inlet to enhance the rotational flow of air introduced to an inside of the second cyclone through the inlet.