Until 1 January 2007 Jernløse municipality was a municipality (Danish, kommune) in northeastern West Zealand County on the island of Zealand (Sjælland) in Denmark.
Its last mayor was Annica Granstrøm representing Venstre, Denmark's Liberal Party.
The site of the municipal council was the town of Nørre Jernløse.
It was merged with existing Holbæk, Svinninge, Tornved, and Tølløse municipalities to form a new Holbæk municipality.
This created a municipality with an area of 583 km2 and a total population of 66,611 (2005).