An image forming apparatus including a storage device storing, from among data to be retained when the power is shut off, either or both of important protection data, being a type determined to be important in advance, and protection data, to be retained when the power is shut off other than the important protection data, at respective predetermined timings. A detection information acquirer receives detection information from a sensor detecting at least one of: a change in either or both of direction and tilt, vibration, a predetermined operation, an approaching person, a person entering a room, and a person entering a predetermined area. A protection processor starts processing for writing either or both of the important protection data and the protection data into the storage device in response to the detection information received by the detection information acquirer, at timings different from the predetermined timings.