The inside of a casing constituting an indoor unit of an air-conditioning apparatus is laterally divided by an air passage partition so that an air passage chamber housing an indoor fan and an indoor heat exchanger is defined close to a casing side panel. A space in the casing close to the casing side panel is further vertically divided by a partition having through holes so that a pipe connection chamber housing parts of the extension pipes, flare joints, and indoor pipes is defined in an upper portion and a pipe draw-out chamber in which the extension pipes are arranged is defined in a lower portion. Gaps between outer peripheries of the extension pipes and inner peripheries of the through holes are filled with insulations.