A fuel cell stack enclosure is provided that includes side covers configured to be joined with each of end of a stack module respectively. A lower cover is also configured to be provided under the stack module and formed to partially cover a lower portion and a first side portion of an outer surface of the side cove. An upper cover may be provided over the stack module, and be formed to partially cover an upper portion and a second side portion of the outer surface of the side cover to enclose the stack module along with the lower cover while joining with the side covers.