A portable electronic apparatus comprises one or more protrusion structures on a surface of the portable electronic apparatus. The protrusion structure comprises a plurality of facets, and one or more peaks are formed on the junctions of the facets. The facets are preferably in the form of triangles or quadrangles, and the protrusion structure is in the form of a pyramid of a triangular base or a quadrangular base. In an embodiment, the protrusion structure is formed on the back housing of the portable electronic apparatus, so that an electronic device, e.g., a digital camera module, embedded in the back housing can be protected to minimize the likelihood of damage.