There is provided a key structure of an operation section of an electronic device that can avoid an occurrence of operational errors of erroneously pressing down an operation key and can reliably secure a large area for input operations and for indicating information. The key structure of the operation section of the electronic device having a plurality of the operation keys 14, 14, . . . arranged in parallel in a manner to be adjacent to one another. The operation portion having a step height (wall surface 23) is formed in the operation key that can perform input operations by being pressed down with a finger of an operator. The operation portion of the operation key is made up of a higher step surface located in a higher level portion in a pressed-down direction and a lower step surface formed at least on an adjacent side where the operation keys are adjacent to one another in a level portion lower than the higher step surface in the pressed-down direction. Each of the higher step surface and the lower step surface is formed so as to be approximately planar and a width of the lower step surface is set to be not less than a half of an error width W of the press-down operation as a width in an adjacent direction with respect to the higher step surface.