An image processing device for restoring a high resolution image from an input image, comprising: weight calculation means (50, 51) for determining an area where a feature value, which is one of a tone of luminance, a luminous intensity, a difference in color, or a difference in chroma, of the input image is saved, based on a gradient of a feature value of a pixel of the input image and a direction of the gradient, and calculating a weight for reducing a regularization constraint that is a constraint based on regularization of image processing in the area where the feature value is saved; regularization term calculation means (30, 31) for calculating a regularization constraint of the high resolution image by using the weight; reconstruction constraint calculation means for calculating a reconstruction constraint that is a constraint based on reconstruction of the high resolution image; and image restoring means (40, 41) for restoring the high resolution image from the input image based on the regularization constraint and the reconstruction constraint, wherein the weight calculation means (50, 51) comprising: gradient calculation means for calculating a gradient of a feature value of a pixel of the input image and a mask calculated by using a sum of squares of the gradients; direction calculation means for calculating a degree of equality in directions of gradient of the feature values based on a first matrix of which elements are calculated by using eigenvalues of a second matrix of which elements are gradient components of values of the pixels; and weight data calculation means for calculating the weight based on the mask and a degree of equality in the directions. weight calculation means (50, 51) for determining an area where a feature value, which is one of a tone of luminance, a luminous intensity, a difference in color, or a difference in chroma, of the input image is saved, based on a gradient of a feature value of a pixel of the input image and a direction of the gradient, and calculating a weight for reducing a regularization constraint that is a constraint based on regularization of image processing in the area where the feature value is saved; regularization term calculation means (30, 31) for calculating a regularization constraint of the high resolution image by using the weight; reconstruction constraint calculation means for calculating a reconstruction constraint that is a constraint based on reconstruction of the high resolution image; and image restoring means (40, 41) for restoring the high resolution image from the input image based on the regularization constraint and the reconstruction constraint, wherein the weight calculation means (50, 51) comprising: gradient calculation means for calculating a gradient of a feature value of a pixel of the input image and a mask calculated by using a sum of squares of the gradients; direction calculation means for calculating a degree of equality in directions of gradient of the feature values based on a first matrix of which elements are calculated by using eigenvalues of a second matrix of which elements are gradient components of values of the pixels; and weight data calculation means for calculating the weight based on the mask and a degree of equality in the directions. gradient calculation means for calculating a gradient of a feature value of a pixel of the input image and a mask calculated by using a sum of squares of the gradients; direction calculation means for calculating a degree of equality in directions of gradient of the feature values based on a first matrix of which elements are calculated by using eigenvalues of a second matrix of which elements are gradient components of values of the pixels; and weight data calculation means for calculating the weight based on the mask and a degree of equality in the directions.