An image processing apparatus comprising: a storage unit configured to store image data read by scanning, with a linear sensor including pixels arranged in a main-scanning direction, an original in a sub-scanning direction orthogonal to the main-scanning direction, an acquisition unit configured to acquire inclination information indicating inclination of the image data, and a readout unit configured to read out the image data from the storage unit, with shifting, in accordance with the inclination information, a line position in the sub-scanning direction by each predetermined number of pixels in the main-scanning direction, wherein the readout unit reads out the image data from the storage unit, based on the inclination information, differentiating the predetermined number of pixels between an edge in the main-scanning direction and other parts.