An oven comprising: a cavity for cooking food; a cavity rear panel placed at a rear of the cavity; and a first tray for being ascended/descended in the cavity, the oven further comprises: an ascending/descending guide part installed at both lateral sides of the front surface of the cavity rear panel; an ascending/descending rack including ascending/descending connection parts (73, 74) engaged with the ascending/descending guide part, the ascending/descending rack is guided by the ascending/descending guide part to ascend and descend; a first tray frame connecting part provided to the ascending/descending rack; a first tray frame coupled to the first tray, the first tray frame is connected to the first tray frame connecting part; and a rear cover placed between the first tray and the cavity rear panel, characterized in that the rear cover is provided at the front of the ascending/descending guide part for shielding the ascending/descending guide part and the ascending/descending connection parts (73, 74) from a space where the first tray ascends and descends and that exposes the first tray frame connecting part frontward. a cavity for cooking food; a cavity rear panel placed at a rear of the cavity; and a first tray for being ascended/descended in the cavity, the oven further comprises: an ascending/descending guide part installed at both lateral sides of the front surface of the cavity rear panel; an ascending/descending rack including ascending/descending connection parts (73, 74) engaged with the ascending/descending guide part, the ascending/descending rack is guided by the ascending/descending guide part to ascend and descend; a first tray frame connecting part provided to the ascending/descending rack; a first tray frame coupled to the first tray, the first tray frame is connected to the first tray frame connecting part; and a rear cover placed between the first tray and the cavity rear panel, characterized in that the rear cover is provided at the front of the ascending/descending guide part for shielding the ascending/descending guide part and the ascending/descending connection parts (73, 74) from a space where the first tray ascends and descends and that exposes the first tray frame connecting part frontward. an ascending/descending guide part installed at both lateral sides of the front surface of the cavity rear panel; an ascending/descending rack including ascending/descending connection parts (73, 74) engaged with the ascending/descending guide part, the ascending/descending rack is guided by the ascending/descending guide part to ascend and descend; a first tray frame connecting part provided to the ascending/descending rack; a first tray frame coupled to the first tray, the first tray frame is connected to the first tray frame connecting part; and a rear cover placed between the first tray and the cavity rear panel, characterized in that the rear cover is provided at the front of the ascending/descending guide part for shielding the ascending/descending guide part and the ascending/descending connection parts (73, 74) from a space where the first tray ascends and descends and that exposes the first tray frame connecting part frontward.