Korean societal concern for the train accidents is fast and widely increasing with an ever-increasing demand and use for KTX. Most of these train accidents are inclined to be caused by human error. Experts used to attribute the causes of human error to the defects in various aspects such as technology, organizational system, practices, corporate culture, and/or human resource itself. Among the diverse causes of human error, an important one, even though it was rarely focused, may be the issue of impact of rule or procedure change on human error. Giving attention to the implicit importance of this issue, this study intends to highlight the theme of frequent procedure change in railway driving manual as a critical factor of human error. To attain this purpose mentioned above, dual methodologies were adopted. One is to qualitatively analyze the real cases of procedure change in relevant manuals followed by the incident case(passing the station scheduled to stop) happened lately. Another is to quantitatively perform statistical analysis based on questionnaires received from 224 train drivers. Results show that frequent changes in internal affairs procedure is or may be an important factor causing stress and human error from train drivers.