A jig for measuring an object shape includes a plate having a first surface and a second surface opposed to the first plate and two reference balls fixed to the plate, each ball surface being exposed on both the first and second surfaces. A reference plane is fixed to the plate, the reference plane having a first plane and a second plane that are parallel to each other, the first and second planes being exposed on the first and second surfaces of the plate, respectively. An object-holding portion is fixed to the plate, the object-holding portion having a hole passing through the plate, the object-holding portion being able to hold an object in the hole with the front and back surfaces of the object being exposed on the first and second surfaces of the plate, respectively.