In this study, rrethyl methacrylate (NtMA)-modified unsaturated polyester mortar, in which the .MMA was added to the unsaturated polyester resin, was developed for improving the early-age strength and the workability of the conventional pol~ concrete, binder of which was the unsaturated polyester resin. Then the strength properties of the .MMA-modified unsaturated polyester mortar were surveyed. The experiIrental results showed that early-age strength was greater when the MMA contents were increased in the range of 20-40%, but the strength rather showed a tendency of decrease when the .MMA contents was 50%.