Background: Nausea and vomiting (emesis) is one of the commonest symptoms during pregnancy. The Pregnancy Unique Quantification of Emesis (PUQE: Koren et al., 2002) is one of the most widely used measures of emesis. Aim: To validate the 24-hour version of the PUQE (PUQE-24) in a population of pregnant Japanese women. A second aim was to identify the severity ranking of PUQE-24 scores. Methods: Approximately 1,500 pregnant women at gestational weeks before 20 were recruited for antenatal checkups at a general hospital and five private clinics in the Tokyo metropolitan area and Kagoshima Prefecture in Japan from January 2017 to May 2019. About a quarter (n = 378) of the participants responded to the questionnaire. They were distributed a set of questionnaires, including the PUQE-24. Results: PUQE-24 scores significantly correlated with younger gestational age, scores on the Health-Related Quality of Life for Nausea and Vomiting during Pregnancy, reduced changes in fluid and meal intake, Sheehan Disability Scale, and depression scores. A two-step cluster analysis with a fixed number of clusters at 4 yielded four groups: Severe, Moderate, Mild, and No Symptoms. Receiver operating characteristic (ROC) analysis produced the best cutoff points for these four groups (3/4, 6/7, and 7/8). They reported excellent specificity, sensitivity, and positive and negative predictive values. Conclusion: Our findings indicate that a cutoff point of 6/7 may be suitable for clinical uses in pregnant women.