Abstract: An indoor unit of an air conditioner wherein a pipe retaining member retaining auxiliary piping connected to a heat exchanger is disposed near both a lateral side and an underside of a mounting frame. The pipe retaining member is bent in an L-shape, and its short plate is exposed on the underside of the mounting frame. The pipe retaining member can be removed only by slightly separating a lower part of the mounting frame from a wall in the fixed state of the indoor unit to the wall. Since the heat exchanger can be separated from the mounting frame without disconnecting the auxiliary piping from communication piping, maintenance work such as washing of the heat exchanger is efficiently performed without requiring much time and effort for separating the auxiliary piping from the communication piping.