Abstract: A retaining device for a replaceable hanger frame comprises a main supporting post and a retainer. The retainer encloses the main supporting post, and a buckle sleeve in the enclosing sleeve. A lower end of an inner surface of the enclosing sleeve is installed with a cambered groove. The buckle sleeve is formed by two opposite wave-like cambered sheets which are assembled to the interior of the enclosing sleeve. The wave-like cambered sheet of the buckle sleeve is installed with a plurality of stop ribs. The wave-like cambered sheets have outer tips which resist against the enclosing sleeve. A concave space formed on the outer surface of the buckle sleeve and an inner surface of the enclosing sleeve provides a margin for compressing and deformation as the main supporting post is engaged. Thereby, the enclosing sleeve and buckle sleeve are positioned to a predetermined position of the main supporting post.