An imaging device, comprising: a first mono-color image sensor configured to detect all wavelength bands of light including red light, green light and blue light and to output a mono-color first image, the first mono-color image sensor comprising a plurality of first micro lenses and a plurality of first light receiving sensors, each of the plurality of first light receiving sensors being configured to detect light passing through a corresponding one of the plurality of first micro lenses and convert the light into an electrical signal; and a second color image sensor comprising a plurality of second micro lenses, a plurality of second light receiving sensors, and color filters provided between one or more micro lenses of the plurality of second micro lenses and one or more light receiving sensors of the plurality of second light receiving sensors, each of the plurality of second light receiving sensors being configured to detect light passing through a corresponding one of the plurality of second micro lenses and convert the light into an electrical signal; characterized in that the first mono-color image sensor and the second color image sensor are mutually independent cameras, in that at least some of the plurality of the first light receiving sensors or at least some of the plurality of second light receiving sensors are set to be phase difference pixels that detect phase difference information for an object, said phase difference pixels made in pairs, each phase difference pixel including a phase separation structure; and that the imaging device is configured to obtain an image by synthesizing the mono-color first image obtained through the first mono-color image sensor and another image obtained through the second color image sensor. a first mono-color image sensor configured to detect all wavelength bands of light including red light, green light and blue light and to output a mono-color first image, the first mono-color image sensor comprising a plurality of first micro lenses and a plurality of first light receiving sensors, each of the plurality of first light receiving sensors being configured to detect light passing through a corresponding one of the plurality of first micro lenses and convert the light into an electrical signal; and a second color image sensor comprising a plurality of second micro lenses, a plurality of second light receiving sensors, and color filters provided between one or more micro lenses of the plurality of second micro lenses and one or more light receiving sensors of the plurality of second light receiving sensors, each of the plurality of second light receiving sensors being configured to detect light passing through a corresponding one of the plurality of second micro lenses and convert the light into an electrical signal; characterized in that the first mono-color image sensor and the second color image sensor are mutually independent cameras, in that at least some of the plurality of the first light receiving sensors or at least some of the plurality of second light receiving sensors are set to be phase difference pixels that detect phase difference information for an object, said phase difference pixels made in pairs, each phase difference pixel including a phase separation structure; and that the imaging device is configured to obtain an image by synthesizing the mono-color first image obtained through the first mono-color image sensor and another image obtained through the second color image sensor.