An image forming apparatus, to which a replaceable unit with a nonvolatile memory is mounted, including: a storage portion configured to store data related to the replaceable unit read from the memory and hold stored contents even when the image forming apparatus is not activated; a door to be opened when the replaceable unit is replaced; a detector configured to detect whether the door is open or closed; a latch circuit configured to hold a specific state when the detector detects that the door is open when the image forming apparatus is not activated; and a controller configured to, when activating the image forming apparatus, read the data from the memory when the latch circuit is in the specific state, read the data from the storage portion when the latch circuit is not in the specific state, and perform an activation process based on the read data.