The pharmacokinetics of daikenchuto (TJ-100), a pharmaceutical-grade traditional Japanese medicine, were investigated in healthy Japanese volunteers after a single oral administration of 2.5-, 5-, and 10-g doses. Six ingredients [hydroxy-α-sanshool (HAS), hydroxy-β-sanshool (HBS), [6]-shogaol (6S), [10]-shogaol (10S), ginsenoside Rb₁(GRB1), and ginsenoside Rg₁(GRG1)] of TJ-100 were determined by using liquid chromatography-tandem mass spectrometry. The results indicated that HAS, an ingredient derived from Zanthoxylum piperitum fruit, exhibited the highest plasma concentration among the six ingredients investigated. The plasma concentrations of HAS, HBS, 6S, and 10S reached the maximum concentration (approximately 400, 80, 0.14, and 0.6 ng/ml, respectively, after a 5-g administration of TJ-100) within 30 min after administration, and the mean half-life was approximately 2 h. Thus, these compounds were rapidly absorbed and eliminated. The plasma concentration of GRB1 reached the maximum concentration (2 ng/ml after a 5-g administration of TJ-100) at approximately 4 h after administration and the half-life of GRB1 was approximately 40 h. The plasma concentration of GRG1 was extremely low (<0.023 ng/ml). The pharmacokinetics of HAS, HBS, 6S, and 10S, were linear within the range of 2.5 to 10 g/day of TJ-100. On the other hand, the kinetics of GRB1 and GRG1 were not proportional to dosage, and plateauing was observed.