To improve sensitivity by adding pixels, and improve precision of pixel interpolation in an imaging device.An imaging device is provided in which pixels are added along a horizontal direction or a vertical direction to improve sensitivity of an imaging element. An R pixel signal, a G pixel signal, and a B pixel signal in which pixels are added, for example, along the vertical direction are output from a CCD (12). A CFA interpolation unit (24) interpolates the G pixel signal using an adjacent pixel along the horizontal direction. The CFA interpolation unit (24) also interpolates the R pixel signal and the B pixel signal along the horizontal direction using an adjacent pixel along the horizontal direction and interpolates along the vertical direction using correlation of the interpolated G pixel.