In order to examine the occurrence of burnt meat in yellowtail Seriola quinqueradiata, fish were processed by different slaughter methods, including instantaneous killing and after being allowed to struggle in sea water for 15 min or in air for 5 min, and the biochemical properties of the muscle tissues were investigated. The muscle from instantaneously killed fish maintained increased pH and adenosine triphosphate（ATP）content compared with fish that struggled； however, the muscle from fish that had struggled showed immediate decreases in ATP and pH. Muscle tissues at various pH levels were then incubated at 26, 28, and 30℃ for 10 min and the changes in Hunter’s whiteness were compared. Muscle held at 26℃ did not show a change in color between pH 5.4 and 6.4. Muscle held at 28℃ also showed hardly any changes in color at pH >6.0, but the muscle showed increasing Hunter’s whiteness with decreasing pH at pH <6.0. Similarly, muscle held at 30℃ showed increasing Hunter’s whiteness with decreasing pH. These results suggest that both body temperature and pH are closely related to the occurrence of burnt meat in yellowtail.