Objective: Despite the significance of trigeminal pathology, practical clinical tests that accurately evaluate intranasal trigeminal function are scarce. The aim of the present study is to introduce a practical procedure for the assessment of intranasal trigeminal sensitivity. Methods: We developed a device to stimulate the nasal mucosa using carbon dioxide, which is self-administered intranasally by holding down a timed button until the required sensory response has been triggered. The trigeminal sensitivity is derived from the measured administration time in conjunction with the concentration of carbon dioxide administered. Sixty-three healthy participants were used to validate the device, after which the new device was compared with a standard lateralization task in an additional 16 participants. In 20 participants, the experiment was repeated to verify test-retest reliability. Results: Statistical analysis showed significant consistency in administration-duration in healthy individuals, including those in the test-retest group. Those participants with higher scores in the lateralization task were found to show higher intranasal sensitivity measured by the new device. Conclusion: Herein, we present the design and validation of a novel device for the practical assessment of intranasal trigeminal sensitivity. In this study, we demonstrate the efficacy and reliability of this device.