There have been few studies related to ELISA for mackerel. In this study we developed a sandwich ELISA for mackerel in processed foods using rabbit polyclonal antibodies against mackerel parvalbumin, the major allergen of mackerel and heat-stable protein. The parvalbumin was purified by ammonium sulfate precipitation and Sephadex G-50 column chromatography. From the standard ELISA curves, the detection limit of parvalbumin was 3 ng/mL and the detection range of mackerel was 5-5,000 ${mu}g/mL$. We further investigated the cross-reactivity of the antibodies toward mackerel, mackerel pike, salmon, flatfish, armorclad rockfish, cod fish, squid, shrimp, blue crab, and lobster. The antibodies were specific for mackerel only. The mean assay recoveries in cooked cream soup, baby food, sausage, and sauce spiked with 0.01 to 0.3% mackerel were 104, 101, 54, and 0%, respectively. In sample tests of 16 commercial items, the qualitative coincidence ratio of assay result and indication was 75%.