Rosh Pinah Jewish Primary head Anthea Abery is to retire at the end of term.
Ms Abery, 61, said she had been waiting until the recent completion of an Ofsted inspection at the 472-pupil school.
Deputy head Judy Greenberg will become acting head and the school will advertise for Ms Abery’s replacement in the new year.
She was appointed head in 2003 after five years in the deputy’s role.
“I believe that now is the time to step aside gracefully and let someone new take the school into the next phase of its development,” she said. “It was my wish to prepare the school for a full inspection from Ofsted and Pikuach before I departed.
“Although the findings are not published at this point, the local authority and I anticipate a very positive and favourable report. I believe the school is now in a very strong position for my successor.”