An object of the present invention is to provide a holding jig that is used for applying a liquid bath treatment to a planar workpiece, has good cleaning capabilities, and avoids intimate contact of the planar workpiece with a rear member of the holding jig so that the planar workpiece can be easily detached from the holding jig after cleaning. A holding jig is used for applying a liquid bath treatment to a planar workpiece. The holding jig comprises a rear member, and a front member that faces the rear member and has an opening portion. The planar workpiece is disposed between the rear member and the front member, and the rear member has a plurality of projections formed on the surface of the rear member facing the front member.