Provided is a mounting base member used in a pair for mounting an object to be conveyed thereon, the mounting base member including: a body part configured to support the object to be conveyed; and a top plate part that extends in at least a horizontal direction from an upper part of the body part. The top plate part covers an upper surface of the body part, or the upper surface of the body part contacting the conveyed object is flush with an upper surface of an extending portion of the top plate part.