Powder mine wastes cause secondary environmental problems from dust flying around villages. It is necessary to recycle to prevent this secondary pollution and to use its beneficial contents. Magnesium and iron may play a role like that of aluminum in geopolymer forming. In this study, therefore, we analyzed the compressive strength of geopolymer prepared from melting slag (MS) and high-magnesium iron mine waste (MW). The compressive strength increased by increasing the mixing ratio of MS and decreasing the L/S ratio. The optimal properties were obtained at a mixing ratio of MS to MW of 5 : 5, molar ratio of SiO2/Na2O of 1.8, and L/S ratio of 0.2. Under these conditions, the compressive strength at 28 days was 112.5 MPa. According to the FT-IR analysis, a geopolymer structure was identified. As a result, we confirmed the possibility of geopolymer forming from MS and MW.