To shorten the time required for a substrate alignment process.

The substrate alignment device includes a first table which holds one substrate, a second table which is movably arranged to face the first table and holds the other substrate, a first microscope which is movably arranged to face the first table and observes an index provided to the surface of one substrate held by the first table, a second microscope which is arranged to face the second table and observes an index provided to the surface of the other substrate held by the second table, a control part which aligns one substrate and the other substrate with each other based on the observation result about the index of one substrate using the first microscope as well as the observation result of the index of the other substrate by the second microscope, and a third table which is arranged to adjoin either the first table or the second table and receives at least either one substrate or the other substrate which is to be aligned next time during, at least, either observation or alignment.