Indonesia's manufacturing industry is the backbone of national economic growth. The requirement of production targets to maintain customer satisfaction leads to a higher workload at any given time. In the manufacturing industry, organizations have divisions according to their business functions, namely core, and non-core. Each department has its workload and function. The workload determines the work stress risk level. So the researchers will do survey research on the influence of sources of stress on the level of work stress risk in each department with a study case of a manufacturing industry employee. The causes of stress based on Indonesia Minister of Manpower Regulation No. 5 of 2018 are role clarity, role conflict, quantitative workload, qualitative workload, career development, and responsibility to others. Then researcher examined using Analysis of Variance (ANOVA), it was found that there was no difference between core and non-core functions in work stress risk level.