The present invention provides a fumigant for wood parasitic nematodes comprising methyl iodide dissolved in liquefied carbon dioxide, in place of methyl bromide the use of which is globally regulated as ozone depleting substance or a fumigant using methyl iodide dissolved in liquefied carbon dioxide in combination with one or more compounds selected from the group consisting of sulfuryl fluoride, methyl isothiocyanate, phosphine, ethylene oxide, carbonyl sulfide and propylene oxide, and a fumigation method for killing wood parasitic nematodes by using said fumigant.