Abstract: The carbon nano-network material is synthesized by the arc discharge of the electrode, which is made of the graphite and metal oxide and placed in the argon atmosphere. The carbon nano-network materials, C 60, C 70, C 76, C 78, C 84 and C 82@La are used as analyzed materials. A series of fragment mass peaks corresponding to the C 2n-loss (n=1,2,3......) of fullerene and metallofullerene molecules are observed in positive mode. The intensities of the fragment ions are found to increase regularly with the increasing size of the carbon cage. Furthermore, intensities for M-C 2nH + ions are found to be higher than those for + in all samples. The results provide us with useful information about the cage structure and stability of carbon nano-network materials.