Since human errors are being recognized as one of the primary issues in safety-critical systems, there is a definite need for systematic analysis of human errors that can identify their types and causes and derive effective countermeasures to help reduce their future probability. This paper proposes a framework for analyzing human errors in safety-critical systems based on analysis of Korean and overseas trends of analyzing human errors in the nuclear power, aviation, railway, offshore oil industry, etc. By using the framework, the investigator or analyst can identify human errors that precede the accident and their types, and can find various causal factors like human factors, task characteristics, work environment, and organizational factors that contribute to them, and can make recommendations to eliminate the causal factors or reduce their effects. A Korean railway accident case is analyzed in the case study.