To provide a sample preparation device capable of suppressing movement of a slide glass at the smearing time.

This blood smear preparation device (sample preparation device) 100 is equipped with a smearing part 2 for preparing a smear on the slide glass 10. The smearing part 2 includes a conveyance part 2e for conveying the slide glass 10, a placing part 71 for placing the slide glass 10, a fixing part 72 for fixing the slide glass 10 placed on the placing part 71, and a driving part 70 for moving the placing part 71 and the fixing part 72.