The purpose of this research is to investigate the relationship between childcare workers’ perception of "child of concern" and preschoolers’ behavioral traits. The Strengths and Difficulties Questionnaire (SDQ) was administered to childcare workers of 902 preschoolers aged 4-5 years, including 470 boys and 432 girls. In addition, we gathered data on "child of concern" using a semi-structured interview individually with childcare worker. A grate number of "child of concern" had high need or some need in conductproblems scale, hyperactivity/inattention scale, and peer problems scale in SDQ. Some behaviors related to developmental disorders were identified in 75.7 percent of "child of concern". On the basis of the results, the following issues were discussed.(1)How do childcare workers perceive "child of concern"? (2)Possibilities and problems of support for preschoolers with developmental disorders.