Are there few junior soccer players (Aged 12 or Younger) competing at middle level who were born between January and March? When does the RAE (Relative Age Effects) start in school year at middle level soccer players? "Middle level" means they are the second highestlevel players with techniques and skills after junior players of Japan Professional Football League. This research was to clarify whether or not the RAE about the month of birth could be realized in middle competition level, and when the RAE could be started in school year. There were few junior soccer players in the 3rd, 5th and 6th grade in school year competing at middle level who were born between January and March. Furthermore, there were many junior soccer players the 6th grade in school year competing at middle level who were born between April and June. The results suggest that the RAE started in the 3rd grade in school year (9 years old) and became the maximum effect in the 6th grade in school year (12 years old). It has also been shown that the circumstance that makes players stop (give up) playing soccer occurs in the third grade of the elementary school.
