A number plate combination type camera apparatus for rear monitoring of a vehicle includes a revolvable case, a camera, a number plate holder. The revolvable case has an opening and a plurality of mounting axles. The camera having a lens is provided in the revolvable case, and the lens is exposed through the opening of the revolvable case. The number plate holder has a rim with front and rear plates, a first opening for exposing part of the number plate, a second opening for exposing the lens of the camera, a case-mounting portion for mounting the revolvable case, a case-axle receptacle for fixing the mounting axle of the revolvable case, and a plurality of fixing devices. The case-mounting portion is formed integrally with the plate holder, and the case-axle receptacle is provided on the rear plate of the rim of the plate holder toward the direction of the vehicle.