A calibration plate is arranged on a support surface of a table. The calibration plate has first and second alignment marks arranged in one direction, and third and fourth alignment marks arranged in another direction that is orthogonal to the one direction. The first and second alignment marks that move in a front-and-rear direction are imaged by a first camera. The one direction of the calibration plate is made parallel to a front-and-rear direction based on the image. The positions of second and third cameras are adjusted based on the third and fourth alignment marks. The second and third cameras, positions of which have been adjusted, are moved to positions below the transfer roller, and a reference line formed at the transfer roller is imaged by the second and third cameras. An orientation of a rotation shaft of the transfer roller is adjusted in a plane parallel to the support surface based on these images.