Abstract: This invention includes an armrest having a combination of a ratchet mechanism with a cam for locking the armrest in an arbitrary inclined state. Three supporting shafts are secured to an armrest frame. A ratchet wheel of semicircular shape includes gear teeth. A first cam is integrally fixed to a circumferential portion of a bracket in which the first supporting shaft is inserted. A second supporting shaft is secured to the armrest frame. A pawl and a second cam are integrally secured to each other. The second cam and the pawl are rotated integrally around the second supporting shaft. The third supporting shaft is fixed to the armrest frame between the first supporting shaft and the second supporting shaft. A third cam is pivotally secured to the third rotatably supporting shaft.