Abstract
We discuss a new realization of N-extended quantum-mechanical supersymmetry (QM SUSY) with central charges hidden in the four-dimensional (4D) mass spectrum of higher dimensional Dirac action with curved extra dimensions. We show that this N-extended QM SUSY results from symmetries in extra dimensions, and the supermultiplets in this supersymmetry algebra correspond to the Bogomol'nyi--Prasad--Sommerfield states. Furthermore, we examine the model of the S² extra dimension with a magnetic monopole background and confirm that the N-extended QM SUSY explains the degeneracy of the 4D mass spectrum.