Blaming "less favourable foreign sales opportunities" for "putting a damper on the development of Swiss industry," analysts from the respected federal institute said its index fell 0.14 points over the month to 1.50.
In October, the barometer "was still as high as 1.64," KOF said in a statement, adding that the figure had been revised down from 1.67.
Researchers at KOF said consumption continued to drive the Swiss economy, but cautioned that its analysis of GDP excluding construction and banking "indicates somewhat gloomier prospects."
Furthermore, the construction sector also appeared to be weakening, while only the banking sector showed positive development, KOF added.
The monthly forecast follows the surprise news on Thursday that Swiss gross domestic product picked up by 0.6-percent in the third quarter compared with second quarter and was up 1.4-percent year-on-year, in contrast with the European Union which has officially entered into recession.
Swiss growth was due to an increase in public expenditure, selected exports and, to a lesser extent, consumer spending, the State Secretariat for Economic Affairs (SECO) said.
Economists, meanwhile, have greeted SECO's positive economic data more circumspectly, warning that the export-heavy Swiss economy could be vulnerable to further deteriorating conditions in Europe, its main trading partner.
Switzerland has faced a central macroeconomic problem during the worst of the eurozone debt crisis, because funds seeking shelter from risk flowed into the Swiss franc, pushing it up and handicapping the Swiss export and tourism sectors.
The central bank has responded with an aggressive strategy of currency intervention to hold the value of the franc down.
Switzerland is not a member of the European Union, but its economy is highly exposed to the health of activity in the eurozone and European Union, which is sluggish.