Asymptotic analysis for the transient scattered field when a pulse wave is incident on the edges of a cylindrically curved conducting open sheet is presented. By applying only the Fourier transform method, we derive a novel time-domain (TD) asymptotic solution. The TD asymptotic solution is represented by a superposition of the transient scattered filed elements arrived at the observation point. The validity of the TD asymptotic solution proposed here is confirmed by comparing with both the reference solution and the experimental-numerical results. We show the interesting phenomenon that the creeping wave propagates along the curved conducting sheet later than the whispering-gallery mode.