Beams is one of structural element which hold bending load and shear loads that are more dominant that axial load. The supports of beam are also very diverse, one of which is cantilever beam. Cantilever beam is a beam that has fixed support at one end and free at the other end. Cantilever beam can be made from many of materials, one of which is steel section. Its light weight and have a large enough strength, and made by fabrication so it has a isotropic material making easier to be applied as a beam structure. But cantilevered structure that has bigger number of internal forces toward its fixed supports, causing usage of uniform steel section becomes less optimal. Therefore, it will be investigated stress and deformation T section steel beam with uniform cross-section with half IWF steel section with diagonal cut so it has non-prismatic section when used as a cantilever beam. In this study, samples are eight different dimension with four couples with the same load to the T section and IWF section and had a comparable size. Analysis is held by using finite element method in a computer program that are freeware, whic are FreeCAD as a 3D drawing program and LISAFEA as calculation program. The result showed that comparable size, the use of half IWF sections with diagonal cut are more efficient looked by the minimum of stress and deformation than uniform T section steel beam.