Effects on the sintering of zircon by minor additives such as $Al_2O_3$, MgO and CaO were studied at $1450^{circ}C$~$1550^{circ}C$ for 30 minutes. Shrinkage, compressive strength, bulk density and apparent porosity of sintered specimens were measured in relation to content of minor additives and temperature. Mineral constitutions of the sintered specimens were idenified with X-ray diffractometer. And microstructures of the sintered specimens were observed by scanning electron microscope. The results obtained were as follow. 1) Effect ofthe minor additives such as Al2O3, MgO and CaO on the sintering of zircon was related to reaction between added oxide and silica by dissociation of zircon. 2) Zircon did not dissociate at $1550^{circ}C$, but it did slightly on the specimen added by Al2O3 5 wt% at $1550^{circ}C$. 3) Sintering of zircon was promoted by the addition of MgO, $(Al_2O_3＋CaO)$ and (MgO＋CaO), then, this phenomenon was due to the formation of liquid phase.