The smaller clearwing moth, Synanthedon tenuis (Butler) (Lepidoptera: Sesiidae), is a major pest of persimmon in northeast Asia. A previous study reported attraction of S. tenuis males to Z3,Z13-18:OAc, but this compound had no effect on male catch in the persimmon orchards in Korea. In this study, we analyzed pheromone gland extracts of S. tenuis females and identified Z3,Z13-18:OH as the main component. In field trapping trial, Z3,Z13-18:OH alone was attractive to S. tenuis males and competitive with live virgin females. These results indicate that the pheromone of this species consists of a single component, Z3,Z13-18:OH. However, Z3,Z13-18:OAc, a previously reported attractant, was not detected in the gland extracts of females. Furthermore, the addition of Z3,Z13-18:OAc to the main pheromone component strongly inhibited attraction for males, suggesting that the diene acetate is not a pheromone component. This is the first report of an octadecadienol as female-produced sex pheromone from the genus Synanthedon.