A vacuum cleaner with a dust collecting device comprising: a case forming an outer appearance of the dust collecting device; a first cyclone, installed within the case, being configured to separate dust from air with foreign objects introduced from one side thereof and discharge the separated dust to a first dust storage unit through an outlet provided at an opposite side thereof; a plurality of second cyclones, arranged along an inner surface of the case, being configured to separate, from the air which has passed through the first cyclone, finer dust that is not separated and discharge the separated finer dust to a second dust storage unit; and a lower cover unit rotatably coupled to one side of the case by a hinge so as to form a bottom surface of the first dust storage unit and the second dust storage unit, being configured to be rotatable by the hinge to simultaneously open/close the first dust storage unit and the second storage unit such that the collected dust and finer dust are simultaneously discharged, characterized in that the vacuum cleaner further comprising: an internal case disposed within the case, having an inner diameter smaller than that of the case; a dust flow channel provided within the internal case to connect the outlet and the first dust storage unit; a fine dust flow channel provided in between the internal case and the case to connect an outlet of the plurality of second cyclones and the second dust storage unit; a sloped portion defining a bottom surface of the fine dust flow channel, being configured to induce movement of the finer dust in the fine dust flow channel to the second dust storage unit; and a step portion forming, together with the internal case, a boundary between the first dust storage unit and the second dust storage unit, extending from the sloped portion to the lower cover unit to form a step between the fine dust flow channel and the second dust storage unit. a case forming an outer appearance of the dust collecting device; a first cyclone, installed within the case, being configured to separate dust from air with foreign objects introduced from one side thereof and discharge the separated dust to a first dust storage unit through an outlet provided at an opposite side thereof; a plurality of second cyclones, arranged along an inner surface of the case, being configured to separate, from the air which has passed through the first cyclone, finer dust that is not separated and discharge the separated finer dust to a second dust storage unit; and a lower cover unit rotatably coupled to one side of the case by a hinge so as to form a bottom surface of the first dust storage unit and the second dust storage unit, being configured to be rotatable by the hinge to simultaneously open/close the first dust storage unit and the second storage unit such that the collected dust and finer dust are simultaneously discharged, characterized in that the vacuum cleaner further comprising: an internal case disposed within the case, having an inner diameter smaller than that of the case; a dust flow channel provided within the internal case to connect the outlet and the first dust storage unit; a fine dust flow channel provided in between the internal case and the case to connect an outlet of the plurality of second cyclones and the second dust storage unit; a sloped portion defining a bottom surface of the fine dust flow channel, being configured to induce movement of the finer dust in the fine dust flow channel to the second dust storage unit; and a step portion forming, together with the internal case, a boundary between the first dust storage unit and the second dust storage unit, extending from the sloped portion to the lower cover unit to form a step between the fine dust flow channel and the second dust storage unit. an internal case disposed within the case, having an inner diameter smaller than that of the case; a dust flow channel provided within the internal case to connect the outlet and the first dust storage unit; a fine dust flow channel provided in between the internal case and the case to connect an outlet of the plurality of second cyclones and the second dust storage unit; a sloped portion defining a bottom surface of the fine dust flow channel, being configured to induce movement of the finer dust in the fine dust flow channel to the second dust storage unit; and a step portion forming, together with the internal case, a boundary between the first dust storage unit and the second dust storage unit, extending from the sloped portion to the lower cover unit to form a step between the fine dust flow channel and the second dust storage unit.