To study the airflow characteristics in human nasal cavities with complex geometries assists in understanding mechanism of nasal stuffiness in breathing. Medical treatment of nasal stuffiness can include ablative surgery using an endoscope, but treatment success depends on the experience of the surgeon, because no objective index has been established to specify the affected areas. This study investigated flow property in simplified nasal cavity models which were matched hydraulic diameter with human nasal cavity. As a result, the fluctuation of the pressure drop between nostril and pharynx in the case of a simplified patient model was in good agreement with the rhinomanometry measurement in the case of a patient. Flow visualization results showed that vortex flow occurred in the nasal vestibule during inspiration.