Researches on metamaterials have realized negative density or stiffness which was impossible previously. However, previous elastic metamaterials were very hard to be applied in various wave systems due to the lack of the independent tunability of negative parameters; the negative density and stiffness were not independently tunable and it was almost impossible to achieve any desired negative material properties. Here, we present the first realization of the elastic metamaterial of which the density and stiffness can be independently tuned. The major advantage of the new elastic metamaterial over the previous one is that the negative density or stiffness is achieved by the independent resonator. Thus, the negative density and stiffness can be independently tuned by different resonators and any desired value of negative density and stiffness can be easily obtained. The detailed wave physics of the proposed elastic metamaterial and its experimental validations will be presented.