This study was designed to test the abrasion resistance of microwave-curing denture base resin. We also studies the effects of surface smoothing treatment on abrasion resistance. Test resin was allowed to polymerize, and then buff polished or treated by surface smoothing. Knoop hardness was measured both prior to and following surface treatment. Then, the test material was subjected to brushing using a newly developed toothbrushing machine. Volume and surface roughness of the material were measured before and after brushing, and the surface structure of the material was examined with SEM. Microwave-curing denture base resin is equal in Knoop hardness and abrasion resistance to its conventional heat-curing counterpart, although it is smoother at the surface. The resin improved both in hardness and abrasion resistance when it underwent surface smoothing treatment regardless of whether it was heat-cured or microwave-cured. As was evident from SEM observations that both types of resins suffered superficial chipping following severe brushing, which is in accordance with our previous clinical findings.