The mass distribution of neutral carbon clusters generated by a laser vaporization of graphite in He was safely determined by a single photon (10.5 eV) ionization technique. The resulting mass distribution was surprisingly different from those reported in previous articles. It was found that the carbon clusters generated under a moderate laser fluence condition (0.1-1 J/cm(2)) consists of mostly even-numbered monocyclic rings with the cluster sizes of n = 10-18. The formation mechanism of such neutral carbon clusters upon laser irradiation is discussed.