The need for examinations of single nucleotide polymorphisms (SNPs) on drug metabolizing enzymes is accelerating. Especially, SNPs of UTG1A1 and CYP2C19 are important for patients who are treated with irinotecan and proton pump inhibitors, respectively. Thus, a method for the rapid, fully automated, and accurate measurement of these SNPs is desired. We genotyped 109 Japanese volunteers for UGT1A1*6, UGT1A1*28, CYP2C19*2, and CYP2C19*3 with the quenching probe (QP) method. Only 90 min after whole blood was applied, QP method enabled to detect these SNPs automatically. The results obtained by QP method were absolutely identical to those examined by the conventional direct sequencing. These findings indicate that the QP method will enable point-of-care testing in clinical laboratories and patient-oriented therapy with its convenience and speed for patients who are treated with irinotecan or proton pump inhibitors.