Air quality displaying system and air quality regulating system

Provided are an air quality displaying system and an air quality regulating system, which can reduce the cost. The air quality displaying system comprises external air quality sensors, which are shared by a plurality of residences forming a congregated housing, are arranged outside the plurality of residences, inspect external air quality of the plurality of residences, and output external air quality signals representing the external air quality. The air quality displaying system comprises internal air quality sensors, which are arranged inside the plurality of residences, inspect internal air quality of the residences, and output internal air quality signals representing the internal air quality. The air quality displaying system comprises controllers, which are arranged at the residences, allow displayers to show corresponding information of the external air quality represented by the external air quality signals and corresponding information of the internal air quality represented by the internal air quality signals. The external air quality signals are transmitted to the controllers of the residences via a network, possessed by the congregated housing, in the congregated housing.