During his petrological study on the inclusions in the garnet-biotite-andesite from Nijo Volcano near Osaka, the present writer pointed out the common occurrence of spinel associating intimately with porphyroblastic andalusite or sillimanite in some xenoliths derived from argillaceous metamorphic rock, as the feature to be observed in xenoliths when they had been enclosed in a volcanic magma., This spinel is not found in the xenoliths slightly or completely metamorphosed by the enclosing magma, but in the ones metamorphosed to a moderate degree., It is conceivable that spinel is formed in xenoliths in an intermediate stage of metamorphism owing to an attacking magma, and disappears when the mutual reaction between the xenolith and magma is more advanced., This consideration coincides with the common occurrence of spinel from xenoliths in effusive or hypabyssal rocks but not from xenoliths in plutonic rocks.,