A cooking appliance comprising: a cavity to provide a cooking chamber; a door to open and close the cooking chamber; a partition plate to partition the cavity into a first chamber and a second chamber, the partition plate facing the door in the closed state, wherein the door closes the first chamber; and a burner assembly disposed in the second chamber to supply heated air into the first chamber, wherein the burner assembly comprises: a burner cover to partition the second chamber into a combustion chamber and an exhaust chamber, a burner disposed in the combustion chamber for burning gas to generate flame, a fan disposed in the exhaust chamber, a nozzle holder disposed outside a rear wall of the cavity, the nozzle holder having a gas spraying hole to spray the gas into the burner, the burner comprises a supply part to receive gas and air, the supply part passing through the rear wall of the cavity, wherein the supply part protrudes toward a rear wall of the cavity, and the gas spraying hole of the nozzle holder aligns with the supply part, wherein the supply part comprises at least one first guide (121, 122) to align the supply part with the gas spraying hole, and wherein the nozzle holder comprises at least a plurality of second guides (224, 225) to guide the at least one first guide (121, 122) of the supply part, wherein a coupling part is disposed on each of the plurality of second guides (224, 225) and coupled to the rear wall of the cavity, wherein the coupling part is bent from the outer end of each of the plurality of second guides (224, 225). a cavity to provide a cooking chamber; a door to open and close the cooking chamber; a partition plate to partition the cavity into a first chamber and a second chamber, the partition plate facing the door in the closed state, wherein the door closes the first chamber; and a burner assembly disposed in the second chamber to supply heated air into the first chamber, wherein the burner assembly comprises: a burner cover to partition the second chamber into a combustion chamber and an exhaust chamber, a burner disposed in the combustion chamber for burning gas to generate flame, a fan disposed in the exhaust chamber, a nozzle holder disposed outside a rear wall of the cavity, the nozzle holder having a gas spraying hole to spray the gas into the burner, the burner comprises a supply part to receive gas and air, the supply part passing through the rear wall of the cavity, wherein the supply part protrudes toward a rear wall of the cavity, and the gas spraying hole of the nozzle holder aligns with the supply part, wherein the supply part comprises at least one first guide (121, 122) to align the supply part with the gas spraying hole, and wherein the nozzle holder comprises at least a plurality of second guides (224, 225) to guide the at least one first guide (121, 122) of the supply part, wherein a coupling part is disposed on each of the plurality of second guides (224, 225) and coupled to the rear wall of the cavity, wherein the coupling part is bent from the outer end of each of the plurality of second guides (224, 225). a burner cover to partition the second chamber into a combustion chamber and an exhaust chamber, a burner disposed in the combustion chamber for burning gas to generate flame, a fan disposed in the exhaust chamber, a nozzle holder disposed outside a rear wall of the cavity, the nozzle holder having a gas spraying hole to spray the gas into the burner, the burner comprises a supply part to receive gas and air, the supply part passing through the rear wall of the cavity, wherein the supply part protrudes toward a rear wall of the cavity, and the gas spraying hole of the nozzle holder aligns with the supply part, wherein the supply part comprises at least one first guide (121, 122) to align the supply part with the gas spraying hole, and wherein the nozzle holder comprises at least a plurality of second guides (224, 225) to guide the at least one first guide (121, 122) of the supply part, wherein a coupling part is disposed on each of the plurality of second guides (224, 225) and coupled to the rear wall of the cavity, wherein the coupling part is bent from the outer end of each of the plurality of second guides (224, 225).