A parallelism adjustment device applicable to nano-imprint lithography has an imprint unit, a carrier unit, a parallelism adjustment mechanism, and a driving source. The imprint unit has a first molding plate and an imprinting mold mounted on the first molding plate. The carrier unit has a second molding plate and a substrate mounted on the second molding plate. The parallelism adjustment mechanism has an enclosed resilient film and a fluid filled therein, and is coupled to at least one of the first and second molding plates. The driving source drives at least one of the imprint unit and the carrier unit to form contact between the mold and the moldable layer. The parallelism adjustment device is pressed via the contact to adjust parallelism for the imprint mold and the substrate and uniformly distributes the pressure between the mold and the substrate, making the molding quality of nano-imprint lithography significantly improved.