To provide a defloration agent and a method of defloration which are free from the danger of decreasing the effect of an agrochemical or the like.

A defloration agent containing an organic acid salt as an active ingredient prevents fertilization by inhibiting the growth of pollen tubes, and as a result it exhibits defloration effect. Since an aqueous solution prepared by diluting the organic acid salt to 100-10,000 times exhibits the defloration effect, the necessary amount of use of the organic acid salt is extremely small. The organic acid salt being water soluble, it forms no coating film over barks or leaf faces by its spray, and thereby even in the case where an agrochemical or the like is sprayed after the spray of the defloration agent, the decrease of the effect of the agrochemical or the like due to the coating film of the defloration agent is not observed. Furthermore, it has no danger of giving ill effect on barks or leaves, or affecting ill effect on a human body, which is observed in a lime sulfur mixture.