Temperature dependence of electrical conductivity and thermoelectricity of trirutile-type ZnSb_2O_6 and (Zn, M)Sb_2O_6 (M=Co, Ni, Cu) ceramics were measured at temperatures ranging from room temperature to 800℃. All samples showed n-type behavior. The conductivity (σ) and thermoelectricity (α) of ZnSb_2O_6 were found to increase with increasing temperature and reached 10^0S・cm^<-1> and 190 μV・K^<-1> respectively, at 800℃. This behavior was explained by considering the carrier electrons to be supplied by oxygen defects and to have thermal activation characteristics. Partial substitution of Zn by Co, Ni, or Cu ions reduced the conductivity and increased the negative Seebeck coefficient. In the present system, a relationship between the apparent activation energies of conductivity and the lattice length of the c-axes of the crystal structure was observed. The measured electrical conductivities were not sufficient for practical use as thermoelectric materials.