It is intended to detect, concentrate and purify aflatoxins of all types which are possibly contained in a sample such as a food. It is also intended to detect the total amount or the individual amounts thereof at a high sensitivity. By using aflatoxin B2 or its derivative as a hapten compound, an antibody, which shows the same reactivity to individual aflatoxin analogs and is highly tolerant to organic solvents, is obtained. Then, a detection/concentration/purification means and an immunological detection means with the use of the above antibody are constructed. The detection means thus constructed achieves a high sensitivity and excellent quantification properties.