The invention provides an indoor unit of an air conditioner. The indoor unit is provided with a support structure of which the end part plays a role in supporting and limiting; and a panel in an opening state can realize self-positioned stable support through the indoor unit, and does not fall off or close under external force; and operators can perform device overhaul and maintenance under safe conditions. The indoor unit comprises a unit body which is arranged on the back of the indoor unit and provided with an air adjusting part, an encloser which seals the unit body from the outside and is connected with the unit body, and the panel connected to the front of the enclose; the panel is provided with an air-inlet grille used for introducing air into the encloser and the unit body, and a filter net which is arranged between the air-inlet grille and the unit body and is used for filtering impurities; the front of the encloser is provided with a concave accommodating groove and a strip support rod; one end of the support rod is provided with a pivot hinged to two sides in the accommodating groove; a positioning rib is arranged on the inside surface of the panel corresponding to the other end of the support rod; and the end part of the accommodating groove hinged with the support rod is provided with a limit lug boss.