A transmission belt manufacturer in Indonesia, producing v-belts and conveyor belts. Many faults remain in the conveyor belt manufacturing process, causing product quality to deteriorate. Bubbles in the canvas cover are responsible for more than half of all faults. As a result, a quality control process is required to ensure that the finished product meets consumer expectations. The percentage of defective goods in total production and the percentage of the main contributors to defects are determined using P control chart approach and Pareto diagram. Fishbone diagrams are used to investigate the sources of faults and prioritize the adjustments that need to be done. The findings revealed that faults in conveyor production are caused by human factors, machinery, and techniques. This study proposes that quality control be used to improve the quality of conveyor products by identifying the major contributors to defects and their causes.