This study looks at individuals who work in social welfare institutions as care staff. We have two purposes of this study, one is to examine associations between the frequency of staff supervision and perceived levels of workload and work intensity among care staff and another is to examine what type of supervision is effective in reducing the working stress of care staff.

　The research design was a cross-sectional survey. The survey was conducted by sending questionnaires to seven social welfare institutions in a rural area in Japan from October to December 2016. Care staff from all institutions returned questionnaires, and the total number of returned questionnaires was 264 (94.0% rate of return). The data were subjected to statistical analysis using SPSS version 24.0. The questionnaire comprised three sections: Supervision Scale, Demographic Characteristics, and Working Conditions. The Supervision Scale was developed by Fukuyama (1998) to measure the frequency of supervision.

　We performed one-way ANOVAs with the workload or the work intensity as the independent variable and the three supervision function scores each as the dependent variables. The three supervision function scores of the "heavy" group were significantly lower than those of the other groups. Administrative supervision function scores of the "not intense" group were significantly higher than those of the "a little intense" group. Supportive supervision function scores of the "not intense" group were significantly lower than those of the "very intense" group.

　A stepwise method of multiple regression analysis was performed to obtain degrees of effects of the supervision statistically. The result was that working stress was significantly related to supportive supervision only (β=-0.246, p=0.002).

　These results show that frequent supervisory sessions can, to a certain degree, reduce supervisees' perceived workload and work intensity and supportive supervision is the most effective ways to reduce the working stress of care staff. If supervisees feel the frequency of supportive supervision is more efficient, their work stress is reduced to some extent.