An indoor unit of an air conditioner includes an indoor unit casing having a first suction port, a panel, a moving mechanism, and a control unit. The panel opens the first suction port by moving so that the panel is spaced apart from the indoor unit casing, and closes the first suction port by moving so that the panel is proximate to the indoor unit casing. The moving mechanism moves the panel so that the first suction port is opened to a desired degree of opening. The control unit controls the moving mechanism. Furthermore, the control unit is capable of modifying the degree of opening of the first suction port to a desired degree of opening.