A latch apparatus of a tailgate for a vehicle is disclosed. The apparatus includes a base supporting a driving motor for supplying power and having an insertion groove for inserting a striker. A latch lever is rotatably disposed close to the insertion groove of the base. The latch lever is pushed to rotate when the striker is inserted into the insertion groove, and covers the striker inserted in the insertion groove. A release unit is disposed close to the latch lever on the base. The release unit is configured to transmit power from the driving motor, fix a position of the latch lever rotating to cover the striker, and allow the latch lever to rotate when the driving motor is operated. A cinching unit, operated by the power from the driving motor, is disposed close to the release unit on the base.