To provide a method for industrially efficiently producing a polyol by omitting a seed culture coming on a production process along with simply and easily adjusting the culture time in main culture.

By sequentially repeating processes composed of a process where a part of the culture solution in producing a polyol is extracted in a microorganism-containing state, a process where microorganisms in the extracted culture solution are inoculated into an other medium and a process where the microorganisms are propagated to produce the polyol, a seed culture process is not required on and after the second production of polyol. By adjusting the amount of culture solution to be inoculated in a range of 0.05-12.5 times the amount of microorganisms inoculated as spawn in a production method requiring a seed culture process, the culture time in the other medium can be adjusted.