Provided is a composite material useful as a material for a thermal contact surface in a microprocessor which can express extremely high thermal diffusion property and extremely high conductivity, can express a sufficient adhesive strength in its surface, and is excellent in reworking property at the time of a bonding operation. The carbon nanotube aggregate of the present invention is a carbon nanotube aggregate where a plurality of carbon nanotubes each having a plurality of walls penetrate a resin layer in a thickness direction of the resin layer, in which both terminals of the carbon nanotube aggregate each have a shear adhesive strength for glass at 25° C. of 15 N/cm2 or more.