Abstract: A method of measuring gas component Concentrations of special material gases for semiconductor, and a semiconductor equipment are provided. The method and apparatus can be incorporated in a gas pipe line system in an inline manner, and measure the component and concentration of a gas flowing through a gas pipe line or a gas with which the gas pipe line system is filled, thereby eliminating any erroneous connection. In the method of measuring gas component concentrations of special material gases for semiconductor, as means for attaining the objects, an infrared gas detector is disposed in a gas pipe line between a gas cylinder containing a special material gas for semiconductor and a semiconductor producing section, so that the gas component and concentration are measured in an inline manner. An apparatus for supplying special material gases for semiconductor is also provided.