An image forming apparatus, configured to perform image formation by forming an image on a sheet and fixing the formed image onto the sheet, comprising: a heater configured to generate heat to heat the sheet over an entire region in a direction perpendicular to a conveyance direction of the sheet to fix the image onto the sheet conveyed after the image is formed on the sheet; a pressing member (30, 31, 33) configured to apply a pressure for fixing to the sheet heated by the heater over the entire region in the direction perpendicular to the conveyance direction; a temperature sensor configured to directly or indirectly measure a temperature of the pressing member (30, 31, 33); a fixing controller configured to control heat generation of the heater such that the temperature measured by the temperature sensor approaches a control temperature; and a processor configured to set, before starting image formation of one job including the image formation, - one candidate temperature of a plurality of predetermined candidate temperatures different from each other as the control temperature on a basis of the number of sheets to be used and a sheet size to be used in the image formation of the one job, characterised by the processor being further configured to set, before starting the image formation of the one job including the image formation, - one candidate speed of a plurality of predetermined candidate speeds different from each other as an image forming speed on a basis of the number of sheets to be used and a sheet size to be used in the image formation of the one job, wherein the processor is configured to set, in a case where a width of the sheet to be used in the direction perpendicular to the conveyance direction is narrower than a predetermined specified width and the number of sheets to be used in image formation of one job including the image formation is larger than a predetermined specified number of sheets, - a first candidate temperature as the control temperature, which is higher than other candidate temperatures to be set as the control temperature in other cases, and - a first candidate speed as the image forming speed, which is slower than other candidate speed to be set as the image forming speed in other cases. a heater configured to generate heat to heat the sheet over an entire region in a direction perpendicular to a conveyance direction of the sheet to fix the image onto the sheet conveyed after the image is formed on the sheet; a pressing member (30, 31, 33) configured to apply a pressure for fixing to the sheet heated by the heater over the entire region in the direction perpendicular to the conveyance direction; a temperature sensor configured to directly or indirectly measure a temperature of the pressing member (30, 31, 33); a fixing controller configured to control heat generation of the heater such that the temperature measured by the temperature sensor approaches a control temperature; and a processor configured to set, before starting image formation of one job including the image formation, - one candidate temperature of a plurality of predetermined candidate temperatures different from each other as the control temperature on a basis of the number of sheets to be used and a sheet size to be used in the image formation of the one job, characterised by the processor being further configured to set, before starting the image formation of the one job including the image formation, - one candidate speed of a plurality of predetermined candidate speeds different from each other as an image forming speed on a basis of the number of sheets to be used and a sheet size to be used in the image formation of the one job, - one candidate temperature of a plurality of predetermined candidate temperatures different from each other as the control temperature on a basis of the number of sheets to be used and a sheet size to be used in the image formation of the one job, characterised by the processor being further configured to set, before starting the image formation of the one job including the image formation, - one candidate speed of a plurality of predetermined candidate speeds different from each other as an image forming speed on a basis of the number of sheets to be used and a sheet size to be used in the image formation of the one job, wherein the processor is configured to set, in a case where a width of the sheet to be used in the direction perpendicular to the conveyance direction is narrower than a predetermined specified width and the number of sheets to be used in image formation of one job including the image formation is larger than a predetermined specified number of sheets, - a first candidate temperature as the control temperature, which is higher than other candidate temperatures to be set as the control temperature in other cases, and - a first candidate speed as the image forming speed, which is slower than other candidate speed to be set as the image forming speed in other cases. - a first candidate temperature as the control temperature, which is higher than other candidate temperatures to be set as the control temperature in other cases, and - a first candidate speed as the image forming speed, which is slower than other candidate speed to be set as the image forming speed in other cases.