A method of producing cement in which mercury contained in dust generated by burning of raw material containing mercury is removed, comprising: using a pre-heater to preheat a cement raw material containing mercury, using a kiln to burn the cement raw material preheated at the pre-heater, using a dust collection unit to collect dust in exhaust gas exhausted from the pre-heater, and using a separation apparatus to separate exhaust gas containing mercury and the dust heated to a temperature equal to or more than a temperature at which mercury can volatilize, characterized in that: the separation apparatus has a first separation unit for separating the exhaust gas and a part of the dust, and a second separation unit provided in a stage subsequent to the first separation unit for separating the exhaust gas and the remainder of the dust, and in that the method further comprises: leading the dust collected by the dust collection unit to an intermediate part of a duct which connects the pre-heater or a kiln back part of the kiln to the first separation unit, supplying bleed gas of 400 to 1100°C bled from the pre-heater or the kiln back part of the kiln to the first separation unit via the duct, putting the dust separated at the first separation unit and the second separation unit into the pre-heater; and using a mercury removal tower to remove mercury from the exhaust gas separated by the separation apparatus. using a pre-heater to preheat a cement raw material containing mercury, using a kiln to burn the cement raw material preheated at the pre-heater, using a dust collection unit to collect dust in exhaust gas exhausted from the pre-heater, and using a separation apparatus to separate exhaust gas containing mercury and the dust heated to a temperature equal to or more than a temperature at which mercury can volatilize, characterized in that: the separation apparatus has a first separation unit for separating the exhaust gas and a part of the dust, and a second separation unit provided in a stage subsequent to the first separation unit for separating the exhaust gas and the remainder of the dust, and in that the method further comprises: leading the dust collected by the dust collection unit to an intermediate part of a duct which connects the pre-heater or a kiln back part of the kiln to the first separation unit, supplying bleed gas of 400 to 1100°C bled from the pre-heater or the kiln back part of the kiln to the first separation unit via the duct, putting the dust separated at the first separation unit and the second separation unit into the pre-heater; and using a mercury removal tower to remove mercury from the exhaust gas separated by the separation apparatus. the separation apparatus has a first separation unit for separating the exhaust gas and a part of the dust, and a second separation unit provided in a stage subsequent to the first separation unit for separating the exhaust gas and the remainder of the dust, and in that the method further comprises: leading the dust collected by the dust collection unit to an intermediate part of a duct which connects the pre-heater or a kiln back part of the kiln to the first separation unit, supplying bleed gas of 400 to 1100°C bled from the pre-heater or the kiln back part of the kiln to the first separation unit via the duct, putting the dust separated at the first separation unit and the second separation unit into the pre-heater; and using a mercury removal tower to remove mercury from the exhaust gas separated by the separation apparatus. leading the dust collected by the dust collection unit to an intermediate part of a duct which connects the pre-heater or a kiln back part of the kiln to the first separation unit, supplying bleed gas of 400 to 1100°C bled from the pre-heater or the kiln back part of the kiln to the first separation unit via the duct, putting the dust separated at the first separation unit and the second separation unit into the pre-heater; and using a mercury removal tower to remove mercury from the exhaust gas separated by the separation apparatus.