UJIA chief executive Doug Krikler has resigned after eight years at the charity to "explore new opportunities".
Mr Krikler joined the charity in September 2004, becoming chief executive in 2005.
Mr Krikler will stay at the charity during its search for a chief executive. He is believed to want to pursue a future in the private sector. Under his leadership, UJIA has invested more than £60m in projects in Israel and £30m in educational projects in the UK.
He said: "I am honoured to have had the opportunity of playing a leading role at UJIA. I have been very fortunate to have had the support of a superb team across the organisation which I know will continue to develop our strategy and build upon the on-going projects. In the past few years UJIA has gone from strength to strength and I have no doubt it will be recognised for the wider role and positive contribution that it has played throughout the community."
UJIA chairman Mick Davis said Mr Krikler was moving on to "broaden his already impressive career." He added: "Doug is a truly outstanding professional. UJIA has been very fortunate to have someone of Doug's skills and experience at the helm and it has been a privilege to work with him."