An image forming apparatus comprising: an image-forming portion that forms an image on a sheet; a detecting unit that detects an amount of deflection of the sheet from a previously set reference position along a sheet width direction which is perpendicular to a transporting direction of the sheet, the detecting unit being positioned at an upstream side of the image-forming portion; a registration roller that is biased to one side of the sheet width direction by a predetermined urging force to shift toward the sheet width direction, the registration roller being positioned at an upstream side of the detection unit; and a control unit that is configured to determine a required shift amount of the sheet on which the sheet is shifted to the reference position based on the amount of deflection of the sheet detected by the detecting unit and to control the registration roller to perform first and second registration roller shift corrections, to shift the sheet toward the sheet width direction based on the required shift amount of the sheet and to send the shifted sheet to the image-forming portion, characterized in that the control unit is also configured to perform the first registration roller shift correction, which is different from the second registration roller shift correction, on a first required shift amount of the sheet when shifting the sheet to a first direction on the sheet width direction to acquire a first specified shift value that includes an amount of correction for correcting an influence by the urging force by which the registration roller is biased or to perform the second registration roller shift correction, which is different from the first registration roller shift correction, on a second required shift amount of the sheet when shifting the sheet to a second direction on the sheet width direction, the second direction being opposed to the first direction, to acquire a second specified shift value that includes an amount of correction for correcting an influence by the urging force by which the registration roller is biased. an image-forming portion that forms an image on a sheet; a detecting unit that detects an amount of deflection of the sheet from a previously set reference position along a sheet width direction which is perpendicular to a transporting direction of the sheet, the detecting unit being positioned at an upstream side of the image-forming portion; a registration roller that is biased to one side of the sheet width direction by a predetermined urging force to shift toward the sheet width direction, the registration roller being positioned at an upstream side of the detection unit; and a control unit that is configured to determine a required shift amount of the sheet on which the sheet is shifted to the reference position based on the amount of deflection of the sheet detected by the detecting unit and to control the registration roller to perform first and second registration roller shift corrections, to shift the sheet toward the sheet width direction based on the required shift amount of the sheet and to send the shifted sheet to the image-forming portion, characterized in that the control unit is also configured to perform the first registration roller shift correction, which is different from the second registration roller shift correction, on a first required shift amount of the sheet when shifting the sheet to a first direction on the sheet width direction to acquire a first specified shift value that includes an amount of correction for correcting an influence by the urging force by which the registration roller is biased or to perform the second registration roller shift correction, which is different from the first registration roller shift correction, on a second required shift amount of the sheet when shifting the sheet to a second direction on the sheet width direction, the second direction being opposed to the first direction, to acquire a second specified shift value that includes an amount of correction for correcting an influence by the urging force by which the registration roller is biased.