A slide operation apparatus capable of ensuring the operability of a knob and improving the visibility of scales on a panel surface of an electronic instrument, without the need of increasing a widthwise space required for mounting the slide operation apparatus on the panel surface. Scales indicating positions in slide movement direction are marked on the panel surface of the electronic instrument on which slide operation apparatuses are mounted. Each slide operation apparatus has a knob adapted to be operated to make a reciprocating slide movement on the panel surface. The knob has its mounting portion whose width is smaller than that of a plate portion and whose left and right end surfaces are receded inwardly from those of the plate portion. The knob has a bottom-side narrow-width portion in which a facing surface is narrower in width in slide movement direction than a finger-operated surface.