An indoor unit of an air conditioner, includes: a main body (2); a discharge port (4) formed on the main body (2) and through which conditioned air is discharged from the main body (2); and a protruding portion (15) formed on an inner surface of the discharge port (4) so as to be positioned at an upstream side (F1) of the conditioned air (CA) with respect to an opening edge (4a) of the discharge port (4) which is an end section of the discharge port (4) at a downstream side of the conditioned air (CA), wherein the conditioned air (CA) is removed from the inner surface of the discharge port (4) by the protruding portion (15) so as to separate from the opening edge (4a) of the discharge port (4), and thereby room air is led into the discharge port (4) through the opening edge (4a) thereof.