This study was conducted to estimate volatile compounds in pericarp of Zanthoxylum piperitum DC (Chopi). Chopi which harvested on lune 2, July 14 and September 11 in 2001 was dried at room temperature for one week. Fifty-two, 47, and 44 volatile compounds were analyzed with GC-MS in pericarp harvested on lune 2, July 14 and September 11, respectively. Eight terpenes including myrcene, ${gamma}$-terpinene, $alpha$-terpinolene, $alpha$-phellandrene and $eta$-caryophyllene were detected in pericarp harvested on tulle 2 and July 14, but not $alpha$-phellandrene and $eta$-caryophyllene in pericarp harvested on September 11. Thirteen alcohols or terpene alcohols including linalool L and citronellol were detected in pericarp harvested on lune 2, and added cis-linallol oxide and piperitol isomer in pericarp harvested on July 14 and September 11. Three aldehydes or terpene aldehydes were not affected by degree of maturation, but citronellal was increased in pericarp harvested on September 11. Five volatile compounds of ketones containing cryptone and piperitone were detected, and their concentration was changed during maturation. Six esters including lavandulyl acetate and $alpha$-terpinenyl acetate were detected in pericarp harvested on lune 2, and [(E)-6,7-ephoxy-3,7-dimethyl-2-octenyl]ester of acetic acid was added in pericarp harvested on July 14 and September 11. Seven hydrocarbons including $delta$-cadinene and neopentylidene cyclohexane were detected in pericarp harvested on June 2 and $alpha$-muurolene was newly added in pericarp harvested on July 14 and September 11. We suggest that kinds and concentration of volatile compounds in pericarp were remarkably different from those in mature stage.