Abstract: An odor intensity index measuring apparatus is provided for measuring odor intensity objectively and easily for various types of odor. Sample air is diluted with odorless air at a desired scale factor in a dilution unit. The diluted air is fed through an air duct to an odorometer. Corresponding to the intensity of odor, voltage V is emitted from the odorometer. In an electronic control unit, the scale factor at which sample air is diluted by the dilution unit is gradually increased. The dilution scale factor which is reached when the output voltage from the odorometer becomes lower than the specified value indicating the odorless condition is displayed on a liquid crystal display. Like the conventional three bag odor comparison method, the odor intensity index can be measured in the same manner for various types of odor. Different from the conventional method, the degree of the odor intensity can be measured objectively without relying on the human sense of smell.