There is provided a dust collecting unit of a vacuum cleaner, the dust collecting unit being designed to increase the density of foreign substances collected in a dust collection container. In the dust collecting unit, a dust collection container collects foreign substances, a top cover closes a top of the dust collection container, a bottom cover closes a bottom of the dust collection container, a compartment plate divides an inner space of the dust collection container into a foreign substance separating compartment and a foreign substance storing compartment, and a bar pushes the compartment plate to the foreign substance storing compartment to compress the foreign substances stored in the foreign substance storing compartment.