PURPOSE: To stabilize the subject solution used for detection of irregular antibody in inspection of human blood transfusion by adding a water-soluble mercury compound in an amount by which the enzymatic activity is not inhibited and a polyhydric alcohol to a bromelain solution.

CONSTITUTION: A water-soluble mercury (e.g. thimerosal, etc.) in an amount not inhibiting the enzymatic activity of bromelain is added as a stabilizer to a purified bromelain solution and further, as necessary, a polyhydric alcohol (e.g. diethylene glycol) is added as a stabilizing auxilizry thereto. The mixture is dissolved in a phosphoric acid buffered physiological saline (pH5.5) and an insoluble matter is removed by centrifugal separation and pH thereof is controlled to 5.0. The supernatant is filtered by a filter and aseptically poured into a vessel to provide the objective stabilized bromelain solution. The bromelain solution is frequently used for detecting an irregular antibody by utilizing a phenomenon wherein IgG type antibody and erythrocyte are agglutinated by the action of bromelain which decomposes the surface glycopeptides of erythrocyte containing sialic acid and N-acetylneuraminic acid, etc., in inspection of human blood transfusion.