A vehicular occupant monitoring system includes a camera disposed at an interior rearview mirror of a vehicle. The camera includes an imaging array sensor and a lens. The lens is disposed at the imaging array sensor with a center axis of the lens vertically offset from a center region of the imaging array sensor. A center region of the lens is disposed at and images at a lower region of the imaging array sensor when the camera is disposed at the interior rearview mirror and an upper peripheral region of the lens images at the center region and a lower region of the imaging array sensor when the camera is disposed at the interior rearview mirror. The vehicular occupant monitoring system, responsive to processing by the image processor of image data captured by the camera, determines presence of an occupant of the vehicle.