A transfer apparatus transfers a first substrate and a second substrate while holding the first substrate and the second substrate to overlap each other in a plan view. The transfer apparatus includes: a first holding arm configured to hold the first substrate in a horizontal direction; a second holding arm configured to hold the second substrate in the horizontal direction; a first detection sensor configured to detect presence/absence of the first substrate held by the first holding arm; and a second detection sensor configured to detect presence/absence of the second substrate held by the second holding arm, wherein the first detection sensor includes a sensor configured to detect the presence/absence of the first substrate, and wherein the first holding arm includes a notch formed at least at an inner end portion of a tip of the first holding arm and configured to allow the optical axis to pass therethrough.