The volatile compounds in the leaves of Japanese pepper (Zanthoxylum piperium DC, sanshoh in Japanese) were obtained by steam distillation, and the potent odorants were evaluated by an aroma extract dilution analysis. (Z)-3-Hexenol and other C-6 compounds, contributing to the grassy aroma character, and citronellal and citronellol were most characteristic of the sanshoh aroma. The glycoside-containing fraction of the methanol extract was obtained by Amberlite XAD-2 adsorption, and then hydrolyzed by β-glucosidase, Rohapect D5L, and acetone powder from fresh sanshoh leaves. (Z)-3-Hexenol, citronellol, benzyl alcohol and 2-phenylethanol were liberated by each enzyme, while geraniol was liberated by Rohapect D5L. These results suggest that the characteristic aroma precursors of sanshoh leaves existed as glycosides.