The concentrations of uranium and thorium in the apatite separated from volcanic rocks are higher than those in dacitic volcanic glasses, but in general far less than those in apatite reported on granitic rocks. The partition of thorium between apatite and groundmass of volcanic rocks is almost constant, but that of uranium varies in a wide range. It seems that the measured partition of uranium between apatite and groundmass is strongly affected by uranium rich small minerals in the apatite. Local concentration of uranium within apatite grains was confirmed by fission track method. The application of apatite for the ionium dating is discussed based on those analytical results and seems to be useful, when the rock sample contains apatite which would be easily separated from the other minerals, for example, by the leaching method.