Provided is a system for removing mercury from a mercury-containing exhaust gas, which contains a mercury chlorinating agent feed unit for feeding a mercury chlorinating agent to an flue exhaust gas containing nitrogen oxide, sulfur oxide and mercury, a reductive denitration unit for reducing the nitrogen oxide, and a desulfurization unit for removing the sulfur oxide, characterized in that the mercury chlorinating agent feed unit further comprises a heating unit for heating a non-gaseous agent for mercury chlorination which is in the non-gaseous form under normal temperature and normal pressure or a gasifying unit for obtaining a gaseous agent for mercury chlorination from the non-gaseous agent for mercury chlorination. The present invention makes it possible to provide a mercury removal process and system which have high reliability and can be operated at a low cost.