Surface resistivity (ρ_s) of polyurethane (PU) films is reduced from 2.1?×?10¹² to 9.4?×?10¹⁰ ohm sq^?1 by addition of 1‐butyl‐3‐methylimidazolium bis(trifluoromethanesulfonyl)imide ([C₄mim][Tf₂N]) for only 10?ppm. Addition of [Tf₂N]‐type ionic liquids (ILs) for 1?000?ppm leads to the reduction of not only ρ_s from 10¹² to 10⁹ ohm sq^?1 but also volume resistivity (ρ_v) from 10⁹ to 10⁷ ohm cm, suggesting that the ILs are uniformly incorporated into the PU films. These PU films have ρ_s in the order of 10⁹ ohm sq^?1 even after methanol washing. The antistatic effects are attributed to ionic conductivity of the PU films, which is achieved by low glass transition temperatures of both PU films and [Tf₂N]‐type ILs. These results suggest that [Tf₂N]‐type ILs are excellent antistatic agents for PUs.