A graphene cantilever beam of arbitrary shape by patterning suspended graphene using a focused ion beam (FIB) is fabricated. Suspended graphene was formed by transferring graphene over a trench structure and patterned the suspended graphene into a cantilever beam structure. When the suspended graphene is patterned by an FIB, the high-ion irradiation of FIB deforms the shape of the cantilever beam; in contrast, low-ion irradiation cannot penetrate the suspended graphene. An evaluation of the ion irradiation dose of the FIB and the damages caused to the suspended graphene confirmed that in the case of few-layer graphene with a maximum of three layers, optimum processing can be performed by an ion irradiation of 6 × 10¹⁶ ions/cm². Under this condition, a graphene cantilever beam with a width of 1.34 μm and a length of 2.13 μm could be fabricated. Furthermore, the Raman spectroscopy results indicate that the FIB process does not significantly change the properties of the graphene.