An auxiliary device for a conveying device that takes out a planographic printing plate precursor from a stack in which a plurality of the planographic printing plate precursors are stacked and that conveys the planographic printing plate precursor, includes: a contact portion configured to come into contact with an edge portion of the planographic printing plate precursor to be conveyed by the conveying device, and the contact portion is formed of an elastic member including a plurality of regions that are disposed at different positions on a trajectory of the edge portion.