The present invention provides a method for producing a carbon nanotube sheet that is excellent in light transmittance and conductivity, and the carbon nanotube sheet. The method includes firstly modifying of modifying a free-standing unmodified carbon nanotube sheet in which a plurality of carbon nanotubes are aligned in a predetermined direction. The firstly modifying includes performing a densification process of bringing the unmodified carbon nanotube sheet into contact with either one of or both of vapor and liquid particles of a liquid substance to produce a modified carbon nanotube sheet that contains the carbon nanotubes which are mainly aligned in a predetermined direction, and that includes a high density portion where the carbon nanotubes are assembled together and a low density portion where density of the carbon nanotubes is relatively lower than density in the high density portion.