In order to provide a fundamental understanding of the cleanroom garment failure, we interviewed the manufacturers and the customers of the garment and studied its modes and mechanism under the simulated and real service conditions. The interviews revealed that the air-born particle was the most critical factor for the failure. The test showed that the abrasion between the fabrics influenced significantly on the air-born particle generation. As the garment was used repeatedly, the number of the air-born particles increased in the oscillating modes. The microscopic study explained the air-born particle generation mechanism.