To provide a vehicle air-conditioning unit that increases a volume of airflow delivered from a side vent opening in a foot mode, to effectively prevent fogging of windowpanes on right and left end sides. An air passage has: a first passage that guides hot air to a center vent opening, a side vent opening, and a defrost opening; and a second passage that is branched from the first passage and guides the hot air to a foot opening. A first door is arranged at a branched position of the air passage to the second passage, and a second door is arranged between the center vent opening and the defrost opening. In a foot mode, the first door closes the first passage and opens a first supply passage, the first supply passage communicates between the first and second passages, the second door closes the center vent opening and forms a second supply passage on an upstream side of the side vent opening, and the second supply passage communicates between an extending direction of the first supply passage and the side vent opening.