Change in permeability during vesiculation has been measured for vesiculated products from decompression experiments. The permeabilities of the experimental products are less than 10-15.5 m2 at vesicularity less than 45 vol %, and increase by about 2 orders of magnitude with the vesicularity increase from 45 to 80 vol %. The permeability-vesicularity relationship of the experimental products is quite different from those obtained for natural eruptive materials by previous measurements, which reported a dramatic increase in permeability from 10-15.5 to 10-13 m2 with vesicularity increase from 2 to 40 vol %. The quenched experimental products can be considered as snapshots in vesiculating magma during decompression. Therefore, the permeability variation in vesiculating magma is close to that obtained from the experiments than that obtained from natural eruptive materials, because the latter has experienced complex deformation in the late stages of eruption.