A method for measuring the presence or absence of an object to be measured in a specimen or the quantity thereof. The method includes filtrating the object to be measured from the specimen using as a physical filter, a void-arranged structural body having a plurality of void portions penetrating in a direction perpendicular to a primary surface thereof so as to hold the object to be measured by the void-arranged structural body; irradiating an electromagnetic wave on the void-arranged structural body holding the object to be measured; and detecting characteristics of an electromagnetic wave scattered by the void-arranged structural body.