The primary taste component of chub mackerel is inosinic acid (IMP). Inosinic acid is generated by ATP degradation after fish death. However, it is degraded to non-taste components by IMP-degrading enzymes (IMPases) over time. Therefore, to maintain the taste of chub mackerel, IMPase activity should be inhibited. Chub mackerel is often processed using liquid seasoning including sugar. Honey is one of the sugar-rich products. As sugar has been reported to inhibit the activity of some types of enzymes, honey is also expected to inhibit IMPase activity. Therefore, in this study, we investigated the effects of honey, its main components (glucose and fructose), and its characteristic components (hydroxymethylfurfural (HMF) and melanoidin) on IMPase activity in chub mackerel. The results indicated that IMPase activity decreased with increasing honey concentration. Furthermore, a relatively high inhibitory effect of fructose was confirmed. Although HMF slightly inhibited IMPase activity, it did not decrease with increasing HMF concentration. In contrast, the IMPase activity decreased with increasing melanoidin concentration. These results indicate that honey has an inhibitory effect on IMPase activity in chub mackerel, and fructose and melanoidin are the main components inhibiting IMPase activity. Thus, honey could be an effective ingredient for processing chub mackerels.