Philippe Ravanas, a company spokesman, said the changes were part of plans started three years ago to increase the integration of the group's senior management.
"Within this context, Xavier said he wanted to pursue other opportunities and I think he will announce something in the next few days."
He denied any suggestion of a boardroom rift between Mr de Mezerac and Philippe Bourguignon, chairman and chief executive, or Gilles Pelisson, executive vice-president, who will temporarily take on the finance director's role.
Mr Ravanas said both of the remaining senior executives had been actively involved in the financial aspects of the business and did not anticipate any problems before a new finance director was appointed. However, he conceded that the role would be "re-defined" first.
Mr de Mezerac's departure came as a surprise to some observers, although shares in the group still rose 0.5p to 118.5p yesterday.
Last month Euro Disney reiterated a warning first made in November that 1997 would be difficult.
Mr Bourguignon said the decision to peg entry charges for the second year running could have a "temporary detrimental impact on margins".