An imager having superior separation properties is provided in which a visible image and an infrared image can be independently and simultaneously obtained. The above imager has a wavelength separation portion of separating an electromagnetic wave carrying an image into wavelengths, and image-taking portions detecting the visible image and the infrared image described above. In the imager described above, at least one of the image-taking portions has a detecting part which is optimized to detect a wavelength component which is to be detected.