To provide an indoor unit which enhances the heat exchange capacity of a heat exchanger, miniaturizes a casing, and prevents degradation of the defrosting capacity even when the air volume is set high.

The height of a heat exchanger 6 is reduced by constituting the heat exchanger provided in a casing 2 a vertical portion 6a, a rear inclined portion 6b, a horizontal portion 6c, and a lower inclined portion 6d. The size of the entire heat exchanger is increased to enhance the heat exchange capacity, and a dew collection means 8 comprising opening/closing panels 8a and 8b, and water discharge gutters 9a and 9b is provided on a lower portion of the horizontal portion 6c. The opening/closing panels 8a and 8b are closed in a cooling mode while they are turned to the position indicated by a broken line and opened in a heating mode. In this configuration, degradation of the defrosting capacity is prevented even when the air volume in the defrosting mode is reduced, and the air volume is set high, and the air volume is increased and the heating capacity is enhanced in the heating mode. Water in the water discharge gutters 9a and 9b is collected in a front dew receiving pan 9 provided on a lower portion of the vertical portion 6a of the heat exchanger 6 via a water passage (not shown).