An image forming apparatus which performs an adjustment operation at appropriate timing. Whether to execute a first or a second adjustment processes is controlled based on the number of sheets on which images are formed. A first adjustment operation is executed in a case where the number of sheets has reached a first number since a previous first adjustment process was executed. A second adjustment operation is executed in a case where the number of sheets has reached a second number since a previous second adjustment process was executed. The first adjustment operation is executed in a case where the number of sheets has reached the first number prior to a designated time by a predetermined period. The second adjustment operation is skipped in a case where the number of sheets has reached the second number prior to the designated time by the predetermined period.