According to the present invention, there is provided a structure of a tail gate formed by bonding peripheral edge portions and their vicinities of an inner panel and an outer panel to each other, and covering a rear portion of a vehicle body so as to freely open and close, wherein a cover is arranged in an inner side of said inner panel, and wherein a lock apparatus provided with a latch capable of engaging with a striker fixed to a vehicle body is disposed between said inner panel and said cover, thereby, it is possible to make it harder to carry out an illegal locking and unlocking operation with respect to a tail gate, with a relatively simple constitution and without increasing number of parts.