A semiconductor substrate alignment device includes: a lower chuck; a lower chuck driving unit; an upper chuck above and overlapping the lower chuck; observation windows in the upper chuck, imaging units respectively configured to irradiate light through the observation windows and to obtain images by detecting light reflected from the semiconductor substrates; a distance sensor configured to detect a distance between an edge of the lower chuck and an edge of the upper chuck; and a control unit configured to identify first and second alignment keys from images of first and second semiconductor substrates, determine an alignment error value of the first and second semiconductor substrates, and compensate for the alignment error value by driving the lower chuck driving unit.