Provided is a camera mounting structure for attaching an in-vehicle camera to a vehicle. An optical protection window cover 503 is inserted into an opening 500 on the vehicle body side together with a camera 500 main body. It is possible to reduce the proportion of the water droplet 502 adhering to the surface of the optical protection window cover 503 with respect to the viewing angle of the camera 500, enabling the observer to visually recognize the presence of the water droplet 502 in visual examination of an image. In addition, the optical protection window cover 503 uses its body 602 to cover the side surface of a camera apparatus main body to implement positional alignment of a camera apparatus.