PURPOSE: To provide an alumina-based composite sintered compact containing silicon carbide fine particles dispersed in alumina particles, having a sufficiently dense structure and having excellent hardness and strength, and to efficiently and stably produce the alumina-based composite sintered product.

CONSTITUTION: 90-97vol.% of alumina powder having an average particle size of ≤0.05μm and 3-10vol.% of silicon carbide powder having an average particle size of ≤0.5μm are mixed with each other, and subsequently subjected to heat treatment at 1150-1350°C to prepare composite particles in which the silicon carbide fine particles are dispersed in the melt-grown alumina particles. The sintering treatment of the molding of the composite particles at 1500-1850°C gives sintered compact with dense composite particles (a porosity of ≤2%) in which the silicon carbide fine particles having a particle size of ≤0.3μm are dispersed in the alumina particles having a particle size of 1.0-10.0μm.