A tightening apparatus for a dental implant includes a torque wrench and a slip detection device. The torque wrench includes a tightening part engageable with an abutment of the implant and a tightening torque detector for detecting tightening torques generated when the abutment is screwed to the fixture. The slip detection device includes a slip determiner and an indicator. The slip determiner samples an amount or rate of change of the torques detected by the torque detector in every predetermined period, to sequentially compare the amount or rate of change of the torques in a prior predetermined period with that in a subsequent predetermined period, and to determine whether or not the latter amount or rate is smaller than the former amount or rate. The indicator activates when the slip determiner determines that the latter amount or rate of change is smaller than the former amount or rate of change.
