An indoor unit for an air conditioner, in which a diffuser outlet through which humidified air is discharged is placed between a front panel and a grill that guides the discharged air, may produce the effect that discharged air pushes discharged humidified air, thereby allowing the humidified air to flow far away from a lateral outlet. As a result, formation of droplets on a surface of the front panel made of a metallic material may be minimized.