In an image forming apparatus, a setting part sets a first waiting time, which lasts from a completion of an ejecting operation of one sheet of recording paper to a start of supply of a subsequent sheet in a one-side printing or a second waiting time, or a second waiting time, which lasts from a completion of ejecting operation of one sheet of recording paper to a start of resupply of the one sheet of recording paper in both-side printing. A determining part detects a difference in time length between the first or second waiting time, a maintenance time required by a head maintenance operation and a cap timer time, which is a time during which a nozzle of the recording head is allowed to be maintained in an uncapped state, and determines a time of restarting a printing operation after execution of the maintenance operation based on the detected difference.