Translucent AlN ceramics with 0-2 wt.% MgF2 additive were prepared by spark plasma sintering. AlN powder was heated temporarily up to 2000 degrees C, before holding at 1850 degrees C for 20 minutes in N-2 gas. The sintered ceramics consisted of a single phase of hexagonal AlN, and showed a transgranular fracture mode. The total transmittance was improved remarkably by the additive, to reach 74% at a wavelength of 800 nm for 1 wt.% MgF2. For 2 wt.% MgF2, the transmittance was slightly lower than that for 1 wt.% MgF2, and an absorption band was observed apparently at around 400 nm. The addition of MgF2 along with the temporary heating at higher temperatures than the sintering temperature contributed to improve the transmittance remarkably.