1. A transfer apparatus for transferring a target substrate, which has optically observable first and second portions, in a semiconductor processing system, the apparatus comprising: a transfer member having a support portion to place the target substrate thereon; a drive unit configured to drive the transfer member so as to transfer the target substrate; a reference mark disposed adjacent to the support portion, and configured to move integratedly with the support portion when the transfer member transfers the target substrate; a storage section, which stores a normal image that shows a positional correlation between the reference mark and the first and second portions, obtained when the target substrate is placed on the support portion at a normal position; an image pick-up device configured to take a detection image that shows a positional correlation between the reference mark and the first and second portions, when the transfer member transfers the target substrate; and an information processing unit configured to obtain a misalignment amount of the target substrate relative to the normal position, based on the normal image and the detection image.