Bleeding (or blood removal) is an important procedure to maintain the quality of fish during chilled storage. The bleeding level is commonly evaluated by analyzing hemoprotein content in fish muscles, but this requires time and effort. The development of a simple and quick technique for quantitatively evaluating the bleeding level in fish muscles is needed. Therefore, we investigated the relationship among visible light image analysis for measuring the change in blood vessel area, color measurement, and hemoprotein content in fish muscles. Horse mackerel Trachurus japonicus was bled by cutting three different locations to analyze hemoprotein content in its muscles. Cutting the gill was the most effective for reducing hemoprotein content in the fish sample compared to the other procedures. The hemoprotein content correlated with the blood vessel area (%) and L ＊ , a ＊ , and b ＊ values of the sample. Notably, hemoprotein content and the dorsal segmental blood vessel area (%) had a high correlation (correlation coefficient R ＝ 0.96, coefficient of determination R 2 ＝ 0.93). These results indicated that the blood vessel area (%) obtained by visible light image analysis can be used to evaluate the bleeding level in horse mackerel muscles.