An image forming apparatus which, to the extent possible, prevents an operation for protecting a printer engine from being uncompleted before power to the printer engine is shut down due to cancellation of a process that should be carried out by the printer engine. When a predetermined time period has elapsed since an instruction to reduce power consumption was detected, power to the printer engine is shut down. When the instruction is detected, a canceling instruction for canceling the process that should be carried out by the printer engine is issued to the printer engine. Responsive to this, a cancellation process for the process is started, and an engine protecting instruction for protecting the printer engine without waiting for completion of the cancellation process is issued to the printer engine. After the operation for protecting the printer engine is carried out, power to the printer engine is shut down.