The present study was conducted to develop “a sex education program for children subjected to sexual abuse” for public health nurses working in child guidance centers, and assess its effectiveness based on changes identified in children who had undergone the program. The subjects were three female children who were subjected to sexual abuse. The program aimed to encourage them to “value their own bodies and minds as well as protect themselves from sexual abuse”, and set eight goals. The program included curriculums developed from the viewpoints of knowledge, cognition, and actions. Changes in children who had undergone the program were assessed by conducting the following three surveys: a questionnaire survey involving the children conducted prior to and following the program, an observation of the children conducted by persons who implemented the program, and interviews with families of the children and care workers in foster homes. According to the results of these surveys, effects related to the eight goals were identified, and it is necessary to provide children with support by implementing sex education on a regular basis combined with advice as part of their daily lives.