A medium alignment apparatus may include an alignment body to form a transfer path is formed for passage of a medium and include an alignment reference surface for alignment of the medium is formed, an alignment roller portion mounted to the alignment body to align the medium while driving the medium simultaneously, and at least one alignment sensor portion to detect whether the medium is aligned by detecting a position of the medium passing along the transfer path. The alignment body may include a first body forming a transfer path for the medium, to which the alignment roller portion is mounted, and a second body disposed at one side of the first body to be movable relative to the first body at a speed corresponding to a transfer speed of the medium, providing a side directed to the first body as the alignment reference surface.