A wall-mounted washing machine includes a rear panel mounted on a porous wall having a plurality of cavities, a tub connected to the rear panel and configured to store washing water, a drum rotatably installed in the tub and configured to wash washing objects, and a fastener unit having one end portion fixed to a fastening hole extending through the cavities of the porous wall and the other end portion configured to extend through the rear panel to fix the rear panel. A first thread is formed in one end portion of the fastener unit. A second thread having a smaller pitch than the first thread is formed in the other end portion of the fastener unit.
