This paper investigates nanomachining of single-crystal silicon using an atomic force microscope with a diamond-tip cantilever. To enable nanomachining of silicon, a nanomachining cantilever with a pyramidal diamond tip was developed using a combination of photolithography and hot-filament chemical vapor deposition. Nanomachining experiments on silicon using the cantilever are demonstrated under various machining parameters. The silicon surface can be removed with a rate of several tens to hundreds of nanometers in ductile mode, and the cantilever shows superior wear resistance. The experiments demonstrate successful nanomachining of single-crystal silicon.