A chemical-mechanical polishing (CMP) apparatus for manufacturing a semiconductor device. The apparatus includes: a spin chuck for supporting and rotating a semiconductor wafer; a polisher comprising a polishing pad for planarizing a surface of the semiconductor wafer, the polisher moving along the surface of the semiconductor wafer by a polishing arm; and a polisher supporting device for supporting the polisher and maintaining the polisher in a horizontal state, while polishing an edge part of the surface of the semiconductor wafer, in order to improve polishing uniformity of a center part and the edge part of the semiconductor wafer. Accordingly, polishing uniformity of the center part and edge part of the semiconductor wafer may be improved, and a height of the polisher supporting device may be optimized according to a polishing degree. Also, the polisher may be easily supported, wear and tear of the support head may be minimized, and the support head may function as a conditioner.