A separation method of Mo from Nb, Zr, and the matrix elements of rubble waste was modified to determine the content of Mo-93 in metal waste. A separation scheme to treat 1 g of metal waste was established by optimizing the amount of ascorbic acid, the rinsing solution, and repeating of the procedure. A thin-layer source was prepared using direct drop deposition and evaporation to measure Mo-93 content. Finally, Mo-93 content in the metal waste generated at the Japan Power Demonstration Reactor was analyzed using the developed method.