Abstract: There is disclosed an immunoassay comprising carrying out an immunological reaction by contacting a fluid sample with an element for immunoassay, having at least three layers of a first detecting layer, a blocking layer and a second detecting layer which are successively laminated, the element containing a substance capable of binding specifically to an immunologically active substance in a fluid sample only in either one of the first and the second detecting layers, and then measuring the detected quantities corresponding to the immunological reaction quantities from both of the first and the second detecting layers.The immunoassay by the use of the immunological analytical element according to this invention improves the precision immunoassay by measuring both of Bound and Free.