A dust collecting device of a vacuum cleaner includes a first cyclone unit comprising a first cyclone chamber where the air enters through a first inlet and spins, and a first dust collecting chamberwhere dust separated from the air is collected; and a second cyclone unit comprising a second cyclone chamber where the air, discharged from the first cyclone unit, enters through a second inlet and spins, and one or more dust collecting parts formed on a circumference of a second cyclone body to separate minute dust from the air upon contacting with the air spinning within the second cyclone chamber. Accordingly, efficiency in collecting minute dust by the dust collecting device increases.