The invention discloses an indoor unit of an air conditioner. The indoor unit of the air conditioner comprises a
machine shell, a rotating air duct piece, a fan
assembly and a door opening and closingdoor. An air inlet is formed in the
machine shell, an air outlet is formed in the rotary air duct piece, an air duct space is formed in the rotary air duct piece, the air outlet and the air inlet areconnected with the air duct space, the rotary air duct piece is rotationally arranged on the
machine shell so as to adjust the air outlet direction of the air outlet, the fan
assembly comprises a first driving motor and an air wheel, the first driving motor is arranged on the machine shell, the wind wheel is arranged inside the air duct space, the first driving motor is connected with the wind wheel to drive the wind wheel to rotate, and the door opening and closing door is movably arranged on the rotating air duct piece to open or close the air outlet. According to the indoor unit of the airconditioner, the air outlet direction of the air outlet can be adjusted through the rotary air duct piece, the air supply range is enlarged, the door opening and closing can move relative to the machine shell to open or close the air outlet, so that not only can the air outlet amount of the air outlet be controlled, but also the sealing performance of the air conditioner indoor unit can be improved.