In the composition according to the embodiment, the content of an unreacted diisocyanate monomer in a urethane-based prepolymer may be controlled to control the physical properties thereof such as gelation time. Thus, since the micropore characteristics, polishing rate, and pad cut rate of a polishing pad obtained by curing the composition according to the embodiment may be controlled, it is possible to efficiently manufacture high-quality semiconductor devices using the polishing pad.