To prevent generation of rattling and to eliminate sinking of a switch panel in the downward direction without producing a clearance between a peripheral edge part of the switch panel and an upper surface part of an arm rest.

A vertical rib part 10 is formed on a back surface part of an engagement click body 9, an engagement groove part is provided on an upper side corner part of a power switch unit 5, and the vertical rib part 10 is inserted and engaged with the engagement groove part of the power switch unit 5 at the time of installing a switch panel 4 in a fitting hole 3a in switch panel installation structure of an arm rest for an automobile devised to cover the power switch unit 5 by engaging the engagement click body 9 at least with a peripheral edge part of this fitting hole 3a from below on the fitting hole 3a provided on an upper surface of the arm rest 3 of a door trim 1 and installing the power switch panel 4.