Contaminant analysis and fault analysis are essential for conducting product quality management and claim response in a wide range of industries, including food, pharmaceuticals, polymers, electrical equipment, and electronics. To accomplish this, product characteristics such as color and shape are observed, and then the most appropriate analysis method is selected. Here, we considered the most common type of contaminant as an example, fiber contaminants. Fiber contaminants include a wide range of substances, such as cotton, acrylic, and polyester, as well as hair of animal origin. Although all of these are easily identified using FTIR, differentiation among those having the same composition is difficult by FTIR. On the other hand, CLSM allows observation of the shape and surface of the sample at the micro level. Here, we introduce examples of analysis of 4 types of fiber contaminants using CLSM and FTIR.