To provide an air conditioner for a vehicle, which achieves reduction in mold cost and man power.

The air conditioner for a vehicle includes: air intake cases 2, 22; and a main case 7 which conditions air taken from the air intake cases 2, 22, in an air conditioning part, and blows out the air from the air blow out part 3 to a cabin 4 side. Each of the air intake cases 2, 22 is constituted in either inside air switching mode, or inside air circulating mode, and the air intake cases 2, 22 are formed separately from the main case 7. The main case 7 can be connected to any one of the air intake case 2 of the inside air switching mode and the air intake case 22 of the inside air circulating mode.