A cooking appliance, comprising: an oven part comprising a cavity having a cooking space therein; a cooktop part comprising a top plate covering an upper portion of the cavity to form an upper space between the top plate and the cavity, and at least one cooktop heating part at least partially disposed in the upper space; a rear cover covering rears of the oven part and the cooktop part to form a rear space between the rear cover and the oven part; an exhaust opening (23, 24) disposed between the cooktop heating part and the rear cover, and formed in a way that passes through the top plate; and a vent grille covering the exhaust opening (23, 24) in an upper portion of the top plate, wherein an upper end opening is formed between the cavity and the rear cover and opens the rear space upward behind the upper space, the top plate connects to the rear cover while covering the upper space and the upper end opening from above, wherein the top plate, comprising: a main plate disposed in an upper portion of the upper space and covering the upper space from above; and an extension plate extended rearward from the main plate and covering the upper end opening from above, wherein the top plate further comprises a coupling part extended from the extension plate and coupled to the rear cover, characterized in that the main plate and the extension plate connect as the same surface while the main plate, the extension plate, and the coupling part are integrated, and the coupling part extends downward from an end portion of a rear of the extension plate. an oven part comprising a cavity having a cooking space therein; a cooktop part comprising a top plate covering an upper portion of the cavity to form an upper space between the top plate and the cavity, and at least one cooktop heating part at least partially disposed in the upper space; a rear cover covering rears of the oven part and the cooktop part to form a rear space between the rear cover and the oven part; an exhaust opening (23, 24) disposed between the cooktop heating part and the rear cover, and formed in a way that passes through the top plate; and a vent grille covering the exhaust opening (23, 24) in an upper portion of the top plate, wherein an upper end opening is formed between the cavity and the rear cover and opens the rear space upward behind the upper space, the top plate connects to the rear cover while covering the upper space and the upper end opening from above, wherein the top plate, comprising: a main plate disposed in an upper portion of the upper space and covering the upper space from above; and an extension plate extended rearward from the main plate and covering the upper end opening from above, wherein the top plate further comprises a coupling part extended from the extension plate and coupled to the rear cover, characterized in that the main plate and the extension plate connect as the same surface while the main plate, the extension plate, and the coupling part are integrated, and the coupling part extends downward from an end portion of a rear of the extension plate. a main plate disposed in an upper portion of the upper space and covering the upper space from above; and an extension plate extended rearward from the main plate and covering the upper end opening from above, wherein the top plate further comprises a coupling part extended from the extension plate and coupled to the rear cover, characterized in that the main plate and the extension plate connect as the same surface while the main plate, the extension plate, and the coupling part are integrated, and the coupling part extends downward from an end portion of a rear of the extension plate.