An indoor unit of an air conditioner, comprising: an indoor unit main body including an inlet and an outlet; a heat exchanger configured to perform heat exchange on air drawn in from the inlet; a cross-flow fan configured to blow out air, which has undergone heat exchange performed by the heat exchanger, from the outlet, wherein the cross-flow fan includes a blow-out flow path formed by a lower wall, left and right side walls, and an upper wall so that a cross-sectional area gradually increases downward, with the blow-out flow path guiding blown-out air to the outlet, and wherein at least part of the blow-out flow path is formed to project out of the outlet at least when an air conditioning operation is performed; a movement mechanism configured to switch between a stored state that does not project an element (26S, 26L, 26U) forming the blow-out flow path out of the outlet and a projected state that projects at least part of the element (26S, 26L, 26U) out of the outlet, wherein the movement mechanism is configured to be in the projected state when an air conditioning operation is performed, and the movement mechanism is configured to be in the stored state when an air conditioning operation is stopped, wherein the side walls each include a movable side wall, the lower wall includes a movable lower wall, the upper wall includes a movable upper wall, characterized in that when a distance in the lower wall from an intersection, where a tangent of a tongue of the cross-flow fan orthogonally intersects the lower wall, to a lower end of the indoor unit main body is referred to as distance L, a ratio (L/D) of the distance L to outer diameter D of an impeller of the cross-flow fan is less than 0.05, and the movement mechanism includes a first movement mechanism configured to move the movable side walls and a second movement mechanism configured to move the movable lower wall and the movable upper wall such that the movable side walls of the side walls are configured to be controlled separately from the movable lower wall of the lower wall and the movable upper wall of the upper wall. an indoor unit main body including an inlet and an outlet; a heat exchanger configured to perform heat exchange on air drawn in from the inlet; a cross-flow fan configured to blow out air, which has undergone heat exchange performed by the heat exchanger, from the outlet, wherein the cross-flow fan includes a blow-out flow path formed by a lower wall, left and right side walls, and an upper wall so that a cross-sectional area gradually increases downward, with the blow-out flow path guiding blown-out air to the outlet, and wherein at least part of the blow-out flow path is formed to project out of the outlet at least when an air conditioning operation is performed; a movement mechanism configured to switch between a stored state that does not project an element (26S, 26L, 26U) forming the blow-out flow path out of the outlet and a projected state that projects at least part of the element (26S, 26L, 26U) out of the outlet, wherein the movement mechanism is configured to be in the projected state when an air conditioning operation is performed, and the movement mechanism is configured to be in the stored state when an air conditioning operation is stopped, wherein the side walls each include a movable side wall, the lower wall includes a movable lower wall, the upper wall includes a movable upper wall, characterized in that when a distance in the lower wall from an intersection, where a tangent of a tongue of the cross-flow fan orthogonally intersects the lower wall, to a lower end of the indoor unit main body is referred to as distance L, a ratio (L/D) of the distance L to outer diameter D of an impeller of the cross-flow fan is less than 0.05, and the movement mechanism includes a first movement mechanism configured to move the movable side walls and a second movement mechanism configured to move the movable lower wall and the movable upper wall such that the movable side walls of the side walls are configured to be controlled separately from the movable lower wall of the lower wall and the movable upper wall of the upper wall.