Abstract: Factors contributed to the causation of accidents in certain metallurgical industry and some machine manufactories have been classified by the authors into three categories, i.e., human, physical and management (including social) factors. Statistics revealed that a high percentage of accidents was attributed to human factors.However, based upon Lenin's theory of reflection and Pavlov's theory of nigher nervous activity, the authors emphasize that most erroneous activities of the workers were mainly determined by inadequate physical conditions, improper training and education, and unsuitable social adjustments, to which, management should be responsible.