Quality control is an important step taken to minimize defective products. Every company, both service and manufacturing, strives to maintain the quality of its products. One of them is the UPTD leather processing in Padang Panjang City which is engaged in leather processing services. Based on the results of the field survey, it was found that there were defects that occurred during the leather processing process such as torn leather and others. The causes of defects in the leather processing process are influenced by several factors such as: humans, materials, the environment and machines. The purpose of this research is to implement quality control using the Six Sigma method and identify the factors that cause defects in the leather processing process using the Six Sigma approach. Six Sigma approach is done by formulating Define, Measure, Analyze, Improve, Control (DMAIC) that occurs in the company. Based on the processing, the Sigma value in the leather processing process in 2018 was 3,086 = 3.0 with a DPMO value of 56398.10 units for a million productions. This value is at level 3 Sigma, meaning that the company needs to improve the quality of the leather processing process to achieve Zero Defect.