Abstract This work addresses a classical molecular dynamics simulation for the clarification of the formation process of fullerene. In particular, we focus our attention on the growth of carbon clusters in a dilute gas phase. Potential functions for carbon atoms used in this work are those proposed by Tersoff, which have been used in the relaxation process of a C60 molecule, Maruyama and Yamaguchi [Chem. Phys. Lett. 286 (1998) 343]. As a result of an 8000-atom simulation with a density of ρ=0.1 nm−3 during 400 ps, various sizes of Cn clusters of n∼100 were obtained, which involved a fullerene-like molecule as well as graphite and chain molecules.