The invention relates to a device for granulating thermoplastic materials with a die plate and a rotary cutter head, said rotary cutter head carrying cutter knives and being positioned in front of said die plate in a water chamber, said rotary cutter head being centered by means of a rocker bearing and being connected in rotationally fixed manner to an axially displaceable drive shaft through a torque transmitting element, the torque transmitting element being in the form of a tubular slotted spring surrounding the drive shaft, said slotted spring connecting the end of the drive shaft facing the rotary cutter head to the rotary cutter head in the peripheral region of the rocker bearing, said rocker bearing being disposed between the end of the drive shaft and the rotary cutter head in the radial direction.