An image forming apparatus improved in a setting process for a recording medium to thereby make it possible to prevent print processing from failing to be executed. In the image forming apparatus including a plurality of sheet feeders for storing recording sheets, when recording sheets are stored in one of the sheet feeders, at least one of the recording sheets is conveyed from the corresponding sheet feeder, and the type of the conveyed recording sheet is identified. Then, the identified type of the recording sheet is set as the type of the stored recording sheets. This makes it possible to prevent occurrence of a situation in which print processing is not executed because the identified type of the recording sheet does not match the set type of the recording sheets, whereby it is possible to prevent print processing from failing to be executed.