A heating cooker including an infrared ray detection device is disclosed. The heating cooker includes a body (10), an inner case (40) disposed within the body, and provided therein with a cooking chamber (20) to cook food, a detection hole (40a) formed at one side wall of the inner case (40), to allow an infrared ray generated in the cooking chamber (20) to exit outwardly from the cooking chamber (20), a path change unit (130) disposed in the vicinity of the detection hole (40a), to change a path of the infrared ray passing through the detection hole, and an infrared sensor (120) disposed to be spaced apart from the path change unit (130), to receive the infrared ray, the path of which has been changed. The path change unit (130) is rotatable to enable the infrared sensor (120) to receive infrared rays having different paths while being generated in different regions in the cooking chamber.