An indoor unit for an air-conditioning apparatus, the indoor unit comprising: a casing, which is to be mounted to a wall surface in a room at a back surface side of the casing; an air inlet (21, 21a, 21b), which is formed in the casing; an air outlet, which is formed in the lower surface of the casing; an indoor heat exchanger and an indoor fan, which are arranged in an air passage continuous from the air inlet (21, 21a, 21b) to the air outlet; an up-and-down airflow direction louver, which is arranged in the air outlet to be able to rotate and is configured to change a direction of blowing air in the up-and-down direction; and an up-and-down airflow direction auxiliary louver, which is configured to, at a position on a front surface side of the casing relative to the up-and-down air flow direction louver, change the direction of the blowing air in the up-and-down direction, a rotational shaft configured to rotate the up-and-down airflow direction auxiliary louver wherein the up-and-down airflow direction louver includes an upstream guide surface, which is configured to guide a flow of the blowing air along the surface of an upstream portion of the up-and-down airflow direction louver, and a downstream guide surface, which is arranged on a downstream side of the blowing air and below the upstream guide surface, and is configured to guide the flow of the blowing air along the surface of a downstream portion of the up-and-down airflow direction louver, and a level difference between the upstream side guide surface and the downstream side guide surface, and the up-down-airflow direction auxiliary louver includes a plate-like portion which is formed on a distal end of an arm portion extending from the rotation shaft in a radial direction of rotation so that a surface of the plate-like portion is substantially parallel to a direction along the rotation direction about the rotation shaft, and wherein when the blowing air blows to the front of the casing, the up-down airflow direction louver is open to downside of the air outlet and forms an air outlet passage of the blowing air, and the up-down airflow direction auxiliary louver is positioned forward of the casing relative to the up-down airflow direction louver, and forms the air outlet passage together with the up-down airflow direction louver, the up-and-down airflow direction auxiliary louver includes an upstream end portion, which is positioned on an upstream side of the air outlet passage, the upstream end portion being positioned above the downstream guide surface and being positioned on the upstream side relative to an end portion of the downstream guide surface and on the downstream side of the level difference. a casing, which is to be mounted to a wall surface in a room at a back surface side of the casing; an air inlet (21, 21a, 21b), which is formed in the casing; an air outlet, which is formed in the lower surface of the casing; an indoor heat exchanger and an indoor fan, which are arranged in an air passage continuous from the air inlet (21, 21a, 21b) to the air outlet; an up-and-down airflow direction louver, which is arranged in the air outlet to be able to rotate and is configured to change a direction of blowing air in the up-and-down direction; and an up-and-down airflow direction auxiliary louver, which is configured to, at a position on a front surface side of the casing relative to the up-and-down air flow direction louver, change the direction of the blowing air in the up-and-down direction, an upstream guide surface, which is configured to guide a flow of the blowing air along the surface of an upstream portion of the up-and-down airflow direction louver, and a downstream guide surface, which is arranged on a downstream side of the blowing air and below the upstream guide surface, and is configured to guide the flow of the blowing air along the surface of a downstream portion of the up-and-down airflow direction louver, and a level difference between the upstream side guide surface and the downstream side guide surface, and