Opportunity of decision making for improving work efficiency is often occurred in work environment. Although typically appropriate task assignment for improving work efficiency is tended to solve as optimization problem, general optimization approach improves task assignment based on quantitative profits for improving work efficiency such as reducing labor cost or shortening operating time. However, actual superior decision maker who is manager expects nurture of worker for improving work efficiency of forthcoming work as qualitative profit by assigning task to inexperienced worker. Therefore, decision making for appropriate task selection by worker should include qualitative profit as criteria. In order to provide appropriate alternative in decision making for improving work efficiency, this paper proposes aggregation of criteria for quantitative profit and qualitative profit by reducing uncertainty of context of worker's situation.