Silicon has been irradiated by singly charged C 60 fullerene ions with an ion dose of up to 1 × 10 13 ions/cm 2 at room temperature in order to study the damage formation of cluster ion bombardment on solid surfaces. Singly and doubly charged fullerene ions and some daughter ions of fullerene were observed. Mass separation was accomplished by a 90° sector magnet. The maximum current of the mass-separated singly charged C 60 fullerene ion beam was about 10 nA. RBS (Rutherford backscattering spectrometry) channeling measurement of the Si(100) bombarded by 300 keV C 60 ions (i.e. 5.0 keV per carbon atom) shows a remarkable increase in the surface peak of the defects even at the low atomic dose of 6 × 10 14 atoms/cm 2. The C 60 fullerene ion beam irradiation produced many defects. This is one of the typical non-linear effects of cluster bombardment.