A structure of an armrest protruding and extending toward a passenger from an inside wall of a vehicle compartment, comprises a trim body portion covering the inside wall, an armrest face portion extending in a substantially horizontal direction from the trim body portion toward an inside, and a support face portion extending continuously from the armrest face portion downward. There is provided a weak portion (deformation promoting portion) between the trim body portion and the armrest face portion to promote deformation with respect to a lateral load. Further, there is provided a garnish covering the weak portion from the vehicle compartment. Accordingly, both sufficient resistance of the armrest in use for the load applied in the vertical direction and proper impact-absorption function of the armrest during the vehicle side collision can be obtained.