Scanning probe lithography based on localized current injection using the probe tip of atomic force microscopy (AFM) has been applied to nanoprocessing of an insulating substrate. An electrically conductive resist film composed of triple layers was developed for this current-injecting AFM lithography. The bottom layer of the resist, which served as a current pass during patterning, consisted of amorphous silicon (a-Si) with 20 nm in thickness prepared by ion-beam sputtering. An organosilane monolayer, that is, octadecylsilyl self-assembled monolayer (ODS-SAM) of 2 nm in thickness, was used as the top layer of the resist, therefore, as the imaging layer in which nanoscale patterns were drawn by AFM. In order to bind the a-Si and the ODS-SAM together, the intermediate layer of the resist, that is, Si oxide of 2 nm in thickness, was prepared by photooxidation of the a-Si layer. Through an AFM-lithographic process using this multilayered resist, nanofabrication of fine grooves on a Si oxide substrate was demonstrated. The minimum feature size about 50 nm was successfully fabricated.