INDOOR UNIT OF AIR CONDITIONER

An indoor unit of an air conditioner according to an embodiment of the present invention includes an outer plate configured to form an exterior of a cabinet installed at a ceiling of an indoor space; an inner case accommodated inside the outer plate, and configured to form an internal space of the cabinet; a fan provided inside the inner case; a heat exchanger disposed to cover an outer side of the fan; a panel configured to shield the cabinet, and having an inlet port through which indoor air is suctioned and a panel outlet port through which heat-exchanged air is discharged; and a drain pan assembly seated on an upper end of the inner case, and configured to collect condensate generated from the heat exchanger, wherein an extending portion which extends to an opened end of the outer plate is formed at a side surface of the inner case corresponding to the panel outlet port, and a recessed portion which is recessed in a shape corresponding to the panel outlet port is formed at an outer end of the drain pan assembly, and both ends of the extending portion are in contact with an inner side surface of the recessed portion, and form an outlet port which is in communication with the panel outlet port.