Police union UPCP has called the "fine strike" in the canton of Geneva to protest against a salary reform for public employees, Swiss broadcaster RTS reported.
The union said the shift could slash the average annual salary of a prison guard, for instance, by 7,000 francs ($7,900).
"We won't be had. The strike is being followed 100 percent," said UPCP chief Christian Antonietti.
The previous such strike in 2012 lasted two weeks, according to RTS.