Metallic CNTs and semiconducting CNTs are efficiently separated from a CNT mixture of these CNTs, and semiconducting CNTs are separated by structure by using a method that enables separation in high yield in a short time period while conveniently enabling mass processing and automatic processing with inexpensive equipment.Multiple columns charged with gel are connected in series, and excess amounts of a CNT dispersion is passed through the columns to adsorb only the CNTs of a specific structure on the columns. The CNTs are then eluted with an elution to separate CNTs of different structures with high accuracy. The present technique represents a method that conveniently enables mass processing and automatic processing at high yield in a short time period with inexpensive equipment.