Background/Objectives: The pyro-drive jet injector (Daicel Injector P1 SC) is a needle-free injection device which propels the medication in a fine jet at high pressure, penetrating the skin to deliver the medication subcutaneously. In this study, we evaluated the safety and efficacy of this jet injector for the administration of seasonal influenza vaccine. Methods: As an open-label and observational case-control study, we compared 30 participants who received the seasonal influenza vaccine (2025-2026) via conventional needle injection with 30 participants who received it via the jet injector to evaluate the immune responses and local and systemic adverse reactions. In 2025-2026 season, a trivalent influenza vaccine covering the A strains (H1N1 and H3N2), as well as the B/Victoria strain was administered. Antibody titers were assessed using hemagglutination inhibition (HI) assays 4 to 12 weeks after vaccination, and seroconversion rate (antibody titer ≥40-fold) was calculated. Results: Regarding the immune response, the seroconversion rates were high for the pyro-drive jet injector group (A/H1N1; 7% vs.37%, P=0.005; A/H3N2; 43% vs. 60%, P=0.196; B; 33% vs. 43%, P=0.426). Similarly, the mean geometric mean titer (GMT) was high with the pyro-drive jet injector (A/H1N1; 5.71 vs.18.68, P=0.001; A/H3N1 19.9 vs.40.63, P=0.042; B 12.42 vs.24.08, P=0.069). Regarding safety, there was no difference in the incidence of local reactions between the two groups with no serious adverse events. Conclusions: The pyro-drive jet injector could offer tolerability comparable to that of a conventional needle and have the potential to enhance immune response for the influenza vaccine.