Disclosed is an oven having a sensor for sensing the air inside a cooking chamber so as to enable the cooked state of food materials to be recognized. The disclosed oven comprises: the cooking chamber; a first passage part disposed outside the cooking chamber so as to communicate with the cooking chamber; the sensor disposed inside the first passage part; a second passage part isolated from the first passage part, and through which forcibly suctioned external air is transferred; and an inlet and an outlet, which allow the first and second passage parts to communicate with each other, wherein, when the inlet is closed, the air inside the cooking chamber flows into the first passage part, and then passes through the sensor so as to be discharged through the outlet, and when the inlet is opened, the air flowing from the second passage part to the first passage part through the inlet passes through the sensor together with the air flowing into the first passage part from the inside of the cooking chamber so as to be discharged through the outlet.