A learning marker configured such that one of learning horizontal distance information and learning vertical distance information can be learned based on detection information from a horizontal travel distance detection device or a vertical travel distance detection device upon detection of at least one edge section of the learning marker in one direction of a horizontal travel direction and a vertical travel direction of a transfer means by a learning marker detector for detecting the learning marker, and the other of the learning horizontal distance information and learning vertical distance information can be learned based on detection information from the horizontal travel distance detection device or the vertical travel distance detection device upon detection of each of both edge sections of the learning marker in the one direction by the learning marker detector.