An fungicide capable of inhibiting the accumulation of the mycotoxin in a crop effectively and a mycotoxin accumulation inhibition method using said fungicide are provided. The mycotoxin accumulation inhibition method according to the invention is a mycotoxin accumulation inhibition method for inhibiting the accumulation of the mycotoxin in a grain after cropping comprising a first fungicide treatment step for treating the cereal plant after the flowering stage with a fungicide containing metconazole as an active ingredient.
