Background: This study aimed to investigate the pedobarographic characteristics of tarsometatarsal instability and to identify factors associated with pedobarographic first tarsometatarsal instability in patients with hallux valgus. Methods: Fifty-seven patients (mean age, 59.7 years; standard deviation, 11.4 years; 6 men and 51 women) with a hallux valgus angle (HVA) greater than 15 degrees were included. All patients underwent a pedobarographic examination along with weightbearing anteroposterior (AP) and lateral foot radiography. Radiographic measurements were compared between the 2 groups with and without pedobarographic first tarsometatarsal instability. The association between the radiographic and pedobarographic parameters of the first tarsometatarsal instability was analyzed using the chi-square test. Binary logistic regression analysis was performed to identify significant factors affecting pedobarographic first tarsometatarsal instability. Results: The HVA (P < .001), intermetatarsal angle (P = .001), and AP talo-first metatarsal angle were significantly different between the pedobarographically stable and unstable tarsometatarsal groups. There was no significant association between radiographic and pedobarographic instability of the first tarsometatarsal joint (P = .924). The HVA was found to be the only significant factor affecting pedobarographic tarsometatarsal joint instability (P = .001). Conclusion: The pedobarographic examination has possible clinical utility in evaluating first tarsometatarsal joint instability in patients with hallux valgus. Patients with a greater HVA should be assessed for the presence of first tarsometatarsal instability, and the necessity of the Lapidus procedure should be considered.