Provided is a method for efficiently purifying an easily polymerizable substance, whereby the operational complexity can be eliminated by, for example, reducing the number of times of cleaning a wire netting. The method according to the present invention for purifying an easily polymerizable substance is characterized by comprising a first separation step for feeding a liquid containing a crude easily polymerizable substance to a distillation column, feeding a column bottom liquid extracted from a recovery part of the distillation column to a wet cyclone, and then separating the column bottom liquid into a liquid containing a first purified easily polymerizable substance and a liquid containing insoluble solids.