An image forming apparatus comprising: a carrier; a forming unit which is configured to form an image on a carrier; a cleaning unit which is configured to clean the carrier; a detection unit which is configured to detect a correction pattern formed on the carrier; and a control unit which is configured to perform a correction processing; characterized in that the image forming apparatus further comprises: a determination unit which is configured to determine a contamination degree of the carrier; and a selection unit which is configured to select, based on the contamination degree, whether or not to perform a first cleaning using the cleaning unit; wherein said correction processing to be performed by the control unit includes, in order: selectively performing the first cleaning on a pattern forming region in the carrier using the cleaning unit if the selection unit selects to perform the first cleaning (S202: Yes, S203: Yes); forming a correction pattern (S208, S215) in the pattern forming region using the forming unit after finishing the first cleaning by the cleaning unit when performed; correcting (S211, S217) an image forming characteristic of the forming unit based on a detection result of the correction pattern by the detection unit; and performing a second cleaning of the carrier by the cleaning unit; wherein the selection unit is configured to select whether or not to perform the first cleaning using the cleaning unit before the control unit controls the forming unit to form the correction pattern during the correction processing. a carrier; a forming unit which is configured to form an image on a carrier; a cleaning unit which is configured to clean the carrier; a detection unit which is configured to detect a correction pattern formed on the carrier; and a control unit which is configured to perform a correction processing; characterized in that the image forming apparatus further comprises: a determination unit which is configured to determine a contamination degree of the carrier; and a selection unit which is configured to select, based on the contamination degree, whether or not to perform a first cleaning using the cleaning unit; wherein said correction processing to be performed by the control unit includes, in order: selectively performing the first cleaning on a pattern forming region in the carrier using the cleaning unit if the selection unit selects to perform the first cleaning (S202: Yes, S203: Yes); forming a correction pattern (S208, S215) in the pattern forming region using the forming unit after finishing the first cleaning by the cleaning unit when performed; correcting (S211, S217) an image forming characteristic of the forming unit based on a detection result of the correction pattern by the detection unit; and performing a second cleaning of the carrier by the cleaning unit; wherein the selection unit is configured to select whether or not to perform the first cleaning using the cleaning unit before the control unit controls the forming unit to form the correction pattern during the correction processing. a determination unit which is configured to determine a contamination degree of the carrier; and a selection unit which is configured to select, based on the contamination degree, whether or not to perform a first cleaning using the cleaning unit; wherein said correction processing to be performed by the control unit includes, in order: selectively performing the first cleaning on a pattern forming region in the carrier using the cleaning unit if the selection unit selects to perform the first cleaning (S202: Yes, S203: Yes); forming a correction pattern (S208, S215) in the pattern forming region using the forming unit after finishing the first cleaning by the cleaning unit when performed; correcting (S211, S217) an image forming characteristic of the forming unit based on a detection result of the correction pattern by the detection unit; and performing a second cleaning of the carrier by the cleaning unit; wherein the selection unit is configured to select whether or not to perform the first cleaning using the cleaning unit before the control unit controls the forming unit to form the correction pattern during the correction processing. selectively performing the first cleaning on a pattern forming region in the carrier using the cleaning unit if the selection unit selects to perform the first cleaning (S202: Yes, S203: Yes); forming a correction pattern (S208, S215) in the pattern forming region using the forming unit after finishing the first cleaning by the cleaning unit when performed; correcting (S211, S217) an image forming characteristic of the forming unit based on a detection result of the correction pattern by the detection unit; and performing a second cleaning of the carrier by the cleaning unit; wherein the selection unit is configured to select whether or not to perform the first cleaning using the cleaning unit before the control unit controls the forming unit to form the correction pattern during the correction processing.