Quality control of a product within a company is a demand to fulfill and achieve product quality by existing standards. With quality control, a problem or defect in the product produced can be seen. Research was conducted in a company that operates in the electricity sector by producing products in the form of ceramic insulators. The problem in this company is that there are still many defects caused by several factors such as human error, environment, and also the methods used. There are 4 types of defects produced, namely broken neck of the product, the broken body of the product, broken leg of the product, and porous defects. This research purpose is to find out the causes of defects from any defects that occurred, then find out solutions or corrective actions to provide on which priority failures need to be reduced. The research was carried out using the Six Sigma method with the DMAIC stages, followed by an FMEA assessment table. After data processing, the capability process (Cp) value was 0.7467, and the Cpk was 0.6477. Then, we obtained a DPMO value is 13,250, so the Sigma level obtained for the last 6 months was 3.72. Then, using FMEA method, we obtained the biggest RPN score is broken body of the product with score 140. So, the improvement suggestion is to check and replace lamps used at glazing stations.