Indoor unit of air conditioning system

An indoor unit body (2) of an air conditioning apparatus having an openable lower surface contains an electrical parts box (13), a heat exchanger (7), a drain pan (10), and an air blower (3) inside. A dress panel (3) closes the opening section of the lower surface of the indoor unit body (2). The drain pan (10) has first insert metal parts (24) for fixing the drain pan (10) to the indoor unit body (2) and second insert metal parts (25) for attaching and fixing the electrical parts box (13) to the drain pan (10). The first insert metal parts (24) and the second insert metal parts (25) are electrically connected and integrally formed with the drain pan (10).