An image forming apparatus including: a memory section having a common storage area that temporarily stores data in an intermediate form, which are generated on the way between image data in a form of page description language and data in a bitmap form obtained by interpreting the image data, and the data in a bitmap form; and a control section configured to monitor a first event that the data in an intermediate form stored in the common storage area have been deleted and a second event that the data in a bitmap form stored in the common storage area have been deleted, and to determine presence or absence of area for the data in an intermediate form to be stored when either of the first and second events occurs.