Yes it does. However, you can remove the seeds using cheesecloth or a strainer. I would strain the seeds out after mashing the fruit and before adding the sugar. Note that this raspberry jam recipe notes that some unwashed raspberries are good! So that means the jam will have a chunkier texture. If you are wanting to remove the seeds, you will need to fully mash the jam, which can affect the thickness/runny-ness of your jam.