The incidence and mortality of colorectal cancer (CRC) have decreased through regular screening colonoscopy, surveillance, and endoscopic treatment. However, CRC can still be diagnosed after negative colonoscopy. Such CRC is called interval CRC and accounts for 1.8–9.0% of all CRC cases. Most cases of interval CRC originate from missed lesions and incompletely resected lesions. Interval CRC can be minimized by improving the quality of colonoscopy. This has led to a growing interest in and demand for high-quality colonoscopy. It is important to reduce the risk of CRC and its associated mortality by improving the quality of colonoscopy. In this review article, we provide an overview of colonoscopy quality indicators, including bowel preparation adequacy, the cecal intubation rate, the adenoma detection rate, the colonoscopy withdrawal time, appropriate polypectomy, and complication of the procedure. Because colonoscopy is a highly endoscopist-dependent procedure, colonoscopists should be well-acquainted with quality indicators and strive to apply them in daily clinical practice for the prevention of CRC.