An image forming apparatus has a changing portion configured to change, based on a detection result of a temperature sensor, response sensitivity in starting of power supply by a determination portion based on a detection result of a human body detection sensor in a case where a human body approaches the human body detection sensor. The changing portion increases the sensitivity in a case where a temperature detected by the temperature sensor is a second temperature lower than a first temperature than in a case where the temperature detected by the temperature sensor is the first temperature.