A cooking appliance comprising: a casing provided with a cooking space therein; a heating unit (H) configured to heat the cooking space : an electronic component space provided outside the casing ; a circuit board disposed in the electronic component space ; a supporter configured to space the circuit board from the casing and support the circuit board ; a cooling fan configured to generate a flow of cool air passing through a cool air passage that is surrounded by the casing , the circuit board and the supporter ; a temperature measuring unit installed at the supporter and configured to measure temperatures in the cool air passage ; and a controller configured to control an operation of the heating unit (H), wherein, the electronic component space is disposed upon the casing , and the supporter comprises an air guide disposed laterally adjacent to the circuit board , protruding from the casing upward, and blocking a lateral side of the cool air passage , characterized in that controlling the operation of the heating unit (H) by the controller is performed based on an increase rate of temperatures measured by the temperature measuring unit , and the temperature measuring unit is installed at the air guide . a casing provided with a cooking space therein; a heating unit (H) configured to heat the cooking space : an electronic component space provided outside the casing ; a circuit board disposed in the electronic component space ; a supporter configured to space the circuit board from the casing and support the circuit board ; a cooling fan configured to generate a flow of cool air passing through a cool air passage that is surrounded by the casing , the circuit board and the supporter ; a temperature measuring unit installed at the supporter and configured to measure temperatures in the cool air passage ; and a controller configured to control an operation of the heating unit (H), wherein, the electronic component space is disposed upon the casing , and the supporter comprises an air guide disposed laterally adjacent to the circuit board , protruding from the casing upward, and blocking a lateral side of the cool air passage , characterized in that controlling the operation of the heating unit (H) by the controller is performed based on an increase rate of temperatures measured by the temperature measuring unit , and the temperature measuring unit is installed at the air guide . an electronic component space provided outside the casing ; a circuit board disposed in the electronic component space ; a supporter configured to space the circuit board from the casing and support the circuit board ; a cooling fan configured to generate a flow of cool air passing through a cool air passage that is surrounded by the casing , the circuit board and the supporter ; a temperature measuring unit installed at the supporter and configured to measure temperatures in the cool air passage ; and a controller configured to control an operation of the heating unit (H), wherein, the electronic component space is disposed upon the casing , and the supporter comprises an air guide disposed laterally adjacent to the circuit board , protruding from the casing upward, and blocking a lateral side of the cool air passage , characterized in that controlling the operation of the heating unit (H) by the controller is performed based on an increase rate of temperatures measured by the temperature measuring unit , and the temperature measuring unit is installed at the air guide . <EOS>