a suction motor mounted in a main body, and generating a suction force;

a filter that collects dust or filth sucked by the suction force generated at the suction motor;

a suction head connected with the filter by a suction tube, and sucking dust and filth on the floor;

a brush installed in the suction head so as to ascend/descend linearly in a generally vertical direction, and sweeping dust and foreign substances into the suction head; and

a brush height control installed in the suction head, to cause the brush to ascend/descend linearly in a generally vertical direction,

wherein the brush height control comprises:

a sliding unit that supports the brush so that the brush can ascend/descend linearly in a generally vertical direction while being rotated;

a switch operated by a user in order to control the height of the brush; and

an operation rod that transmits an operating force of the switch to the sliding unit, and

wherein the sliding unit comprises:

guide members mounted at an inner side surface of the suction head;

a sliding member at which both ends of a hinge shaft extending from both end portions of the brush are rotatably inserted respectively, supported at the guide member so as to linearly move in a vertical direction; and

an elastic member positioned at a lower surface of the sliding member, and providing a certain elastic force that pushes the sliding member upwardly.