Semiconductor gas sensors are device consisting of sintered metal oxides, which can indicate target gas concentration by measuring the electric resistance of device. The gas sensors have been developed widely for detection of inflammable gases, toxic gases, odor gases, environmental-related gases and so on. As the materials, n-type oxides, such as SnO 2, In 2O 3, WO 3 and so on, are well known. For the material design of the semiconductor gas sensor, we have reported important three functions i.e. receptor function, transducer function and utility factor. In this presentation, the material design for high-sensitive detection of environmental-related gases is shown.