The effects of single-walled carbon nanotube (SWCNT) structures on the transparent conductivity of their network films have been investigated. SWCNTs with different average tube diameters of 1.3 nm, 1.7 nm, and 2.0 nm were processed at the same conditions. Then unit structure characterization was performed by determining the tube diameter, length, bundle thickness, and so on, before the fabrication of SWCNT network films by the filtration and transfer method using the dispersions. The result of the transparent conductivity measurements clearly showed better performance with a decrease in the tube diameter: that is, narrower SWCNTs form narrow bundles, and their dense network results in an increase in the total length of conduction pathways in the SWCNT network films with high transparency. Furthermore, the figure of merit and the percolation exponent for the transparent conductivity obtained by using the data fitting of the percolation model were also discussed in terms of the tube diameter and length.