An image interpolation device, which can perform image interpolation at low cost and with low power consumption. The image interpolation device includes a pixel data storage which temporarily and sequentially holds, in the form of a plurality of unit pixel data groups, data of adjacent pixels in the vertical direction of input image data. The image interpolation device also includes an image memory which can store at least three of the unit pixel data groups. Unit pixel data groups held in the pixel data storage are sequentially written to the image memory. At least two unit pixel data groups stored in the image memory are read simultaneously.