A cooker includes a heating chamber configured to accommodate an object to be heated, a heater configured to heat the object to be heated accommodated in the heating chamber, heating controller (14) configured to control the heater for heating, an image capturing unit configured to capture an image inside the heating chamber, and mark detector (28) configured to detect a specific mark from the image captured by the image capturing unit. Heating controller (14) disallows or allows heating by the heater, based on a result of detection by mark detector (28).