An apparatus for inspecting an allergic reaction projects laser light onto an object having a bloodstreams and receives, using a light sensor, light rays scattered by blood cells at the surface of the object. Based on signals output from the light sensor, the apparatus calculates respective relative values of the bloodstreams at a portion of the object subjected to an allergic reaction test, wherein the relative values are relative to an average value of the bloodstreams measured at a portion of the object other than the portion subjected to the allergic reaction test which is not affected by the allergic reaction test. The apparatus displays the obtained relative values.