BPPV is the most common vestibular disorder with good prognosis. The pathophysiology has been debated for long time, but recently canalolithiasis has been credited as the most potential mechanism since physical maneuver and posterior canal plugging operation were developed (Epley 1997; Pames und McClure 1992). However, there are some cases that resist treatments or recur for many times. The mechanism of these cases should be further investigated. One of the feasible approach to pathophysiology of BPPN is to study basic vestibular structure, such as otolith and cupula. In this paper, basic aspects of the ololithic organ and the semicircular canal (SC) cupula as well as model experiments using the isolated labyrinth are presented.