Because of environmental problems, in recent years air-conditioners have been required to improve their fundamental performance such as high efficiency and low energy consumption. From the standpoint of installation, however, air-conditioners must be lighter and more compact. In order to respond to these contradictory needs, an inverter driven packaged air-conditioner has been developed by employing a high performance DC inverter compressor that reduces its seasonal power consumption by 30% and its weight and size by 35 - 60% compared with former model. This paper introduces the newly developed air-conditioner and reports on the methods used to achieve high efficiency, light, weight and compactness.