For developing the vocabulary that can describe the taste characteristic of natural and synthetic extracts of boiled snow crad Chionoecetes opilio, 5 trained panelists first tasted the extracts and selected a total of 18 terms (items), which consist of 9 primary qualities for taste, 8 secondary qualities for taste, and overall taste. Using this descriptive vocabulary, a 30 member panel evaluated the differences in taste between the two extracts. Mean scores of each of the primary qualities showed that the synthetic extract had almost the same intensity of sweetness and sourness as the natural one, but had weaker saltiness, stronger pungency, and somewhat stronger astringency, metallic taste, and alkaline taste. Of the secondary qualities, mean scores for the synthetic extract were lower than those for the natural one in all of the 8 items. Pattern and subtracted pattern similarities calculated for the primary and secondary qualities suggested that preferential increases in saltiness, pungency, bitterness, astringency, naturalness, and viscosity should be effective in reproducing the taste of the natural crab extract. Correlations among the 18 items computed in accordance with the theory of quantification IV showed that umami, sweetness, saltiness, complexity, fullness, naturalness, continuance, viscosity, and extension should be considered first in the preparation of a synthetic extract as a flavoring material.