Image forming apparatus for periodically cleaning print unit and method thereof

An image forming apparatus periodically cleans print units used for printing. The image forming apparatus comprises a print part that prints by using a replaceable print unit, a memory that stores information regarding a condition for cleaning with respect to the print unit, a status detection part that detects an operational status of the print unit, and a controller that controls the print part to clean the print unit if the operational status detected by the status detection part satisfies the condition for cleaning. The print part supplies a printing paper and transfers a foreign substance left on a surface of the print unit to the printing paper, thereby cleaning the print unit. Accordingly, print quality does not deteriorate.