A method of manufacturing a polishing pad includes producing an urethane prepolymer having a viscosity of 20,000 cps (at 25 C.) to 40,000 cps (at 25 C.) by mixing a plurality of polymers, mixing the urethane prepolymer with an inert gas and a low-boiling blowing agent having a boiling point of 60 C. to 150 C., and manufacturing a polishing layer including porous pores by causing a mixture produced at the mixing to be subjected to gelation and curing in a predetermined cast.