A vehicle air-conditioning air blower comprising: a casing having an inside air inlet through which air inside a cabin is introduced into the casing, and an outside air inlet through which air outside the cabin is introduced into the casing, the inside air inlet and the outside air inlet opening to outside, the casing further having a first air passage and a second air passage each communicating with both of the inside air inlet and the outside air inlet, the casing including an inside/outside air switching damper (4,5) that opens and closes the inside air inlet and the outside air inlet; a first blower fan disposed in the first air passage; a second blower fan disposed in the second air passage; and a motor including an output shaft transmitting torque to the first and second blower fans (40,50), the first blower fan sending air in the first air passage as air-conditioning air, the second blower fan sending air in the second air passage as air-conditioning air, wherein the first and second blower fans and the output shaft are arranged so that their rotation axes extend vertically, the casing includes therein an inner peripheral water entry reducing portion including an inner peripheral wall portion, and an outer peripheral water entry reducing portion including an outer peripheral wall portion, the inner peripheral wall portion surrounding the output shaft and substantially preventing water inside the casing from entering the motor, the outer peripheral wall portion surrounding the inner peripheral wall portion outside the inner peripheral wall portion and substantially preventing water inside the casing from entering the motor, the vehicle air-conditioning air blower being characterised in that it further includes a lower wall portion connecting a lower portion of the inner peripheral wall portion and a lower portion of the outer peripheral wall portion together, the lower wall portion is inclined downward toward outside in a radial direction of the output shaft, the inner peripheral water entry reducing portion has at least one inner peripheral opening through which air flows, the outer peripheral water entry reducing portion has at least one outer peripheral opening through which air flows, the at least one inner peripheral opening and the at least one outer peripheral opening are prevented from overlapping with each other in a circumferential direction of the output shaft, and the at least one outer peripheral opening reaches a lower end of the outer peripheral wall portion. a casing having an inside air inlet through which air inside a cabin is introduced into the casing, and an outside air inlet through which air outside the cabin is introduced into the casing, the inside air inlet and the outside air inlet opening to outside, the casing further having a first air passage and a second air passage each communicating with both of the inside air inlet and the outside air inlet, the casing including an inside/outside air switching damper (4,5) that opens and closes the inside air inlet and the outside air inlet; a first blower fan disposed in the first air passage; a second blower fan disposed in the second air passage; and a motor including an output shaft transmitting torque to the first and second blower fans (40,50), the first blower fan sending air in the first air passage as air-conditioning air, the second blower fan sending air in the second air passage as air-conditioning air, wherein the first and second blower fans and the output shaft are arranged so that their rotation axes extend vertically, the casing includes therein an inner peripheral water entry reducing portion including an inner peripheral wall portion, and an outer peripheral water entry reducing portion including an outer peripheral wall portion, the inner peripheral wall portion surrounding the output shaft and substantially preventing water inside the casing from entering the motor, the outer peripheral wall portion surrounding the inner peripheral wall portion outside the inner peripheral wall portion and substantially preventing water inside the casing from entering the motor, the vehicle air-conditioning air blower being characterised in that it further includes a lower wall portion connecting a lower portion of the inner peripheral wall portion and a lower portion of the outer peripheral wall portion together, the lower wall portion is inclined downward toward outside in a radial direction of the output shaft, the inner peripheral water entry reducing portion has at least one inner peripheral opening through which air flows, the outer peripheral water entry reducing portion has at least one outer peripheral opening through which air flows, the at least one inner peripheral opening and the at least one outer peripheral opening are prevented from overlapping with each other in a circumferential direction of the output shaft, and the at least one outer peripheral opening reaches a lower end of the outer peripheral wall portion.