An image processing device comprising: a storage section configured to store a low-resolution frame image acquired based on a light-receiving value, a light-receiving unit being a unit for acquiring the light-receiving value, the light-receiving unit being set corresponding to a plurality of adjacent pixels of a color image sensor, and pixel values (v 00 -v 22) of the plurality of pixels included in the light-receiving unit being added up and read as the light-receiving value of the light-receiving unit; an estimation calculation section configured to estimate pixel values of pixels included in the light-receiving unit based on a plurality of low-resolution frame images stored in the storage section; and an image output section configured to output a high-resolution frame image having a resolution higher than that of the low-resolution frame image based on the pixel values estimated by the estimation calculation section, the low-resolution frame images being acquired in time series by reading the light-receiving value of the light-receiving unit while sequentially performing a pixel shift process by one pixel to the light-receiving unit for each successive image, and light-receiving units obtained by sequentially performing the pixel shift process overlapping each other, and the estimation calculation section being configured for estimating the pixel values of the pixels included in the light-receiving unit based on light-receiving values of the light-receiving units obtained by sequentially performing the pixel shift process, and outputting a high-resolution frame image having a resolution higher than that of the low-resolution frame image based on the estimated pixel values, wherein the color image sensor is a single-chip RGB image sensor. a storage section configured to store a low-resolution frame image acquired based on a light-receiving value, a light-receiving unit being a unit for acquiring the light-receiving value, the light-receiving unit being set corresponding to a plurality of adjacent pixels of a color image sensor, and pixel values (v 00 -v 22) of the plurality of pixels included in the light-receiving unit being added up and read as the light-receiving value of the light-receiving unit; an estimation calculation section configured to estimate pixel values of pixels included in the light-receiving unit based on a plurality of low-resolution frame images stored in the storage section; and an image output section configured to output a high-resolution frame image having a resolution higher than that of the low-resolution frame image based on the pixel values estimated by the estimation calculation section, the low-resolution frame images being acquired in time series by reading the light-receiving value of the light-receiving unit while sequentially performing a pixel shift process by one pixel to the light-receiving unit for each successive image, and light-receiving units obtained by sequentially performing the pixel shift process overlapping each other, and the estimation calculation section being configured for estimating the pixel values of the pixels included in the light-receiving unit based on light-receiving values of the light-receiving units obtained by sequentially performing the pixel shift process, and outputting a high-resolution frame image having a resolution higher than that of the low-resolution frame image based on the estimated pixel values, wherein the color image sensor is a single-chip RGB image sensor.