Provided is a vehicle air conditioning device including an air conditioning unit in which: a unit case (10) of the air conditioning unit is formed of a plurality of lower and upper divided cases (23, 24, 25); and the divided cases (23, 24, 25) are coupled integrally to each other through a mating portion (34) provided to division end surfaces (30A, 30B, 32). The vehicle air conditioning device also includes a space (35) having a given height in the top-bottom direction and a given width is formed between respective case inner division end surfaces (32, 30B) of the divided cases (24, 25) on one side and the divided case (23) on the other side, the divided cases (23, 24, 25) constituting the mating portion (34).