An indoor unit of an air-conditioning apparatus, the indoor unit comprising: a casing having an air inlet and an air outlet and including a heat exchanger and an air-sending fan disposed inside the casing; and an up-down airflow direction louver (17, 18) disposed at the air outlet and controlling an up-down airflow direction of air discharged from the air outlet, the up-down airflow direction louver (17, 18) including a first plate (21a, 21b) and a second plate (22a, 22b) joined to each other and a water absorber (24a, 24b) at an end portion of the up-down airflow direction louver (17, 18) on a downstream side of an airflow that passes along the up-down airflow direction louver (17, 18), wherein an end portion of the second plate (22a, 22b) on the downstream side is positioned on the downstream side of an end portion of the first plate (21a, 21b) on the downstream side, and the water absorber (24a, 24b) is held between the first plate (21a, 21b) and the second plate (22a, 22b), and a portion of a water absorption surface (26a, 26b) of the water absorber (24a, 24b) on the downstream side of the airflow is exposed to a side of the warm indoor air, the portion being positioned on the downstream side of the airflow of a portion of the water absorber (24a, 24b) held between the first plate (21a, 21b) and the second plate (22a, 22b), characterized in that the indoor unit is configured so that during cooling operation, the up-down airflow direction louver (17, 18) comes into contact, on a side of the first plate (21a, 21b), with warm indoor air and comes into contact, on a side of the second plate (22a, 22b), with cool air that is heat exchanged by passing through the casing a casing having an air inlet and an air outlet and including a heat exchanger and an air-sending fan disposed inside the casing; and an up-down airflow direction louver (17, 18) disposed at the air outlet and controlling an up-down airflow direction of air discharged from the air outlet, the up-down airflow direction louver (17, 18) including a first plate (21a, 21b) and a second plate (22a, 22b) joined to each other and a water absorber (24a, 24b) at an end portion of the up-down airflow direction louver (17, 18) on a downstream side of an airflow that passes along the up-down airflow direction louver (17, 18), wherein an end portion of the second plate (22a, 22b) on the downstream side is positioned on the downstream side of an end portion of the first plate (21a, 21b) on the downstream side, and the water absorber (24a, 24b) is held between the first plate (21a, 21b) and the second plate (22a, 22b), and a portion of a water absorption surface (26a, 26b) of the water absorber (24a, 24b) on the downstream side of the airflow is exposed to a side of the warm indoor air, the portion being positioned on the downstream side of the airflow of a portion of the water absorber (24a, 24b) held between the first plate (21a, 21b) and the second plate (22a, 22b), characterized in that the indoor unit is configured so that during cooling operation, the up-down airflow direction louver (17, 18) comes into contact, on a side of the first plate (21a, 21b), with warm indoor air and comes into contact, on a side of the second plate (22a, 22b), with cool air that is heat exchanged by passing through the casing