Otolaryngologists typically perform diagnoses and offer medical treatment for vestibular dysfunction. This vestibular dysfunction manifests as benign paroxysmal positional vertigo (BPPV), Ménière's disease, vestibular neuronitis, and so on. The etiology of BPPV is still not clear, so in this article we discuss inner-ear function, etiology, and factors related to BPPV. We examined by pure-tone audiometry and hot and cold caloric tests patients whom we identified as having diagnosed posterior canal-type BPPV. We observed canal paresis at a high rate on the affected side (p < .01). The term of recovery at the first treatment was longer in patients with canal paresis as compared to those without. Deterioration of hearing level was observed more frequently on the affected side (p < .01). The horizontal semicircular canal and cochlea are important potential sites of lesions affecting posterior canal-type BPPV, and the posterior circular canal and otolith are already considered to be sites of affecting lesions.