The present invention provides a sintered body of aluminum nitride comprising (i) aluminum nitride as a main component and (ii) at least one component selected from the group consisting of Zr, Hf, V, Nb, Ta, Cr, Mo, W, Fe, Co, Ni, Nd, Ho, Ti, and compounds thereof in the total amounts of not greater than 1.0 wt. % and not less than 0.01 wt. % in terms of elements on the basis of sintered body, the sintered body being colored and having a thermal conductivity of at least 150 W/mK. The sintered body is useful for the preparation of circuit boards having printed circuits thereon and highly heat-releasing ceramic packages for semiconductive devices.