1. An image processing device comprising: a process output image generation means generating one sheet of a process output image by performing a process using plural sheets of captured images sequentially output from a pickup device in consideration of one of the plural sheets of captured images as a reference image, wherein the process output image generation means includes an image adding means for performing noise reduction in a time direction through addition of the plural sheets of captured images, the noise reduction being performed at the same time that the image adding means compensates for motion between the captured images; and a correction means correcting image distortion occurring in the captured images by an optical pickup system including a pickup lens, with respect to the captured images produced in the process output image generation means, when the plural sheets of the captured images are obtained, wherein the correction means corrects the image distortion after the noise reduction is performed by the image adding means.