A face image capturing apparatus comprising: a camera that repeatedly captures an image of a face of an occupant of a vehicle; an on-axis illuminator that is arranged generally coaxially relative to an optical axis of the camera; an off-axis illuminator that is arranged non-coaxially relative to the optical axis of the camera; an illumination control device (40, 60) that is configured to adjust an illumination condition of light applied to the face of the occupant by controlling a light quantity of light emitted by the on-axis illuminator and a light quantity of light emitted by the off-axis illuminator; an image capturing control device that is configured to control the camera to capture the image of the face at an image capturing timing that is synchronized with a timing for adjusting the illumination condition by the illumination control device (40, 60); and a luminance calculation process device that is configured to perform a luminance calculation process by using following face images: a bright pupil face image (px) captured by the camera under a first illumination condition, in which light is applied to the face mainly by the on-axis illuminator; a dark pupil face image (py) captured by the camera under a second illumination condition, in which light is applied to the face mainly by the off-axis illuminator; and an ambient light face image (pz) captured by the camera under a third illumination condition, in which ambient light around the occupant is mainly applied to the face, wherein the luminance calculation process device is adapted to add a luminance of the bright pupil face image (px) and a luminance of the dark pupil face image (py) to generate an addition face image (px+pv), and subtract a doubled luminance of the ambient light face image (pz) from the addition face image (px+pv) to generate a part detection image (px+pv-2xpz) used for detecting a part that corresponds to the face of the occupant. a camera that repeatedly captures an image of a face of an occupant of a vehicle; an on-axis illuminator that is arranged generally coaxially relative to an optical axis of the camera; an off-axis illuminator that is arranged non-coaxially relative to the optical axis of the camera; an illumination control device (40, 60) that is configured to adjust an illumination condition of light applied to the face of the occupant by controlling a light quantity of light emitted by the on-axis illuminator and a light quantity of light emitted by the off-axis illuminator; an image capturing control device that is configured to control the camera to capture the image of the face at an image capturing timing that is synchronized with a timing for adjusting the illumination condition by the illumination control device (40, 60); and a luminance calculation process device that is configured to perform a luminance calculation process by using following face images: a bright pupil face image (px) captured by the camera under a first illumination condition, in which light is applied to the face mainly by the on-axis illuminator; a dark pupil face image (py) captured by the camera under a second illumination condition, in which light is applied to the face mainly by the off-axis illuminator; and an ambient light face image (pz) captured by the camera under a third illumination condition, in which ambient light around the occupant is mainly applied to the face, wherein the luminance calculation process device is adapted to add a luminance of the bright pupil face image (px) and a luminance of the dark pupil face image (py) to generate an addition face image (px+pv), and subtract a doubled luminance of the ambient light face image (pz) from the addition face image (px+pv) to generate a part detection image (px+pv-2xpz) used for detecting a part that corresponds to the face of the occupant. a bright pupil face image (px) captured by the camera under a first illumination condition, in which light is applied to the face mainly by the on-axis illuminator; a dark pupil face image (py) captured by the camera under a second illumination condition, in which light is applied to the face mainly by the off-axis illuminator; and an ambient light face image (pz) captured by the camera under a third illumination condition, in which ambient light around the occupant is mainly applied to the face, wherein the luminance calculation process device is adapted to add a luminance of the bright pupil face image (px) and a luminance of the dark pupil face image (py) to generate an addition face image (px+pv), and subtract a doubled luminance of the ambient light face image (pz) from the addition face image (px+pv) to generate a part detection image (px+pv-2xpz) used for detecting a part that corresponds to the face of the occupant.