The invention discloses an ultra wide angle camera lens. The ultra wide angle lens comprises a first lens, a second lens, a third lens, a fourth lens and a fifth lens in sequence from an object space to an image space, wherein the first lens, the second lens and the fourth lens have negative focal power, the third lens and the fifth lens have positive focal power, the fourth lens and the fifth lens are adhered together to form a cemented lens with the positive focal power, the condition that BFL (Back Focal Length) / EFL (Effective Focal Length) is not smaller than 2.4 is also satisfied, BFL is a distance from an outermost point at the image space of a fifth lens element of the ultra wide angle camera lens to an imaging plane, and EFL is a focal length value of the ultra wide angle camera lens. In the invention, the ultra wide angle camera lens remains a longer BFL under the condition that a TTL (Total Length of Lens) is kept so as to meet requirements for larger sizes of electronic elements and devices at the periphery of an image sensor during the design of a camera; and the lens elements and optical filters are further from the image sensor due to longer BFL, so that the requirement for the surface cleanliness of the respective lens elements and optical filters can be effectively reduced, and the camera is easier to assemble and produce.