A click module which gives a feeling of click when an operation knob which is tiltably and pivotally supported on a casing of an operation switch is tiltably operated has a click face on which a crest portion or a valley portion is formed, a click element which slides on the click face, and a resilient member which biases the click element to a click face side. The click module is detachably mounted on the casing. The click element and the click face slide relative to each other in an interlocking manner with a tilting operation of the operation knob.