Homogeneous single-walled carbon nanotube (SWCNT) ink, suitable for film formation in wet processes, was prepared using high-pressure emulsification (HPE) with the addition of an efficient dispersant. In the prepared ink, SWCNTs were finely deagglomerated, without being shortened and undergoing structural decomposition. Micropatterning of the SWCNT thin film prepared on polyethylene terephthalate (PET) film substrate, by UV light exposure and water rinsing, was also demonstrated based on the change in photoinduced affinity of the dispersant with respect to the SWCNT surfaces.