A plume (109) is generated by irradiating a side face of a graphite rod (101) with a laser beam (103) to vaporize carbon. The vaporized carbon is introduced to a carbon nanohorn recovery chamber (119) through a recovery pipe (155), and the vaporized carbon is recovered as a carbon nanohorn assembly (117). A cooling tank (150) including liquid nitrogen (151) is arranged in the recovery pipe (155). While the cooling tank (150) controls the plume (109) at a low temperature, the cooling tank (150) cools the carbon vapor when the carbon vapor passes through the recovery pipe (155). The cooled carbon vapor is recovered as the carbon nanohorn assembly (117) which is controlled in the desired shape and dimensions.