Provided are a data management apparatus and a data management method for a surveillance system. The data management apparatus includes: a first storage unit configured to store therein data provided from a data input unit; a second storage unit configured to store therein a copy of the data; and a control unit configured to control the first storage unit to store the data therein on a real time basis, and if the data stored in the first storage unit is equal to or larger than a predetermined threshold amount, generate the copy and control the second storage unit to store the copy in the second storage unit as much as a given amount.