PROBLEM TO BE SOLVED: To provide a dimension measuring apparatus for a metal thin plate, capable of accurately measuring a dimension of a metal thin plate, and a dimension measuring method for a metal thin plate.SOLUTION: A dimension measuring apparatus for a metal thin plate includes: a loading plate on which a metal thin plate is loaded; a pair of retention mechanisms configured to hold two opposite sides of the metal thin plate loaded on the loading plate; a tension mechanism configured to widen a distance of the pair of retention mechanisms to each other so as to impart a tensile strength to the metal thin plate; a suction mechanism configured to adhere on the loading plate the metal thin plate with the tensile strength imparted; and a measurement mechanism configured to measure at least one dimension of the metal thin plate adhered on the loading plate.
