To provide a cement production system capable of achieving effective use and reuse of wastes by producing cement using wastes as a raw material and a fuel.

The cement producing system comprises the steps of thermally decomposing with a thermally decomposing apparatus 2 the wastes crushed into a predetermined size with a pretreatment apparatus 1, classifying the residue of thermal decomposition into iron, a nonferrous metals and carbon including trash in an incombustible material classification processing apparatus 3, ashing the trash and carbon in an atmosphere of oxidation with an ashing processing apparatus 4, and thereafter, crushing the ashed trash and carbon together with other wastes and adjusting components with a raw material crushing apparatus 5 in a cement producing apparatus, mixing with a lime stone prepared in a raw material preparing and mixing apparatus 6, burning the prepared and mixed raw material into a cement clinker in a firing and cooling apparatus 7, and mixing and crushing the cement clinker with a gypsum and, if necessary, a setting agent in a product crusher 8.