To provide an air conditioner for an automobile excellent in assembling workability even with a unit containing a plurality of parts including an evaporator and moreover preventing leakage of condensed water.

A unit case is composed of a pair of longitudinally bisected cases 1a, 1b. A protruding part 23 formed along a joint face 21 of one case 1a is formed at the joint face 21 of one case 1a, and a recessed part 24 into which the protruding part 23 is inserted and engaged is formed at a joint face 22 of the other case 1b. A seal member 25 is interposed between the protruding part 23 and the recessed part 24, and storage parts 27 for accommodating the seal member 25 pushed out in case of jointing both cases are formed near the joint faces 21, 22 of the cases 1a, 1b.