A shrink fit adapter for a collet chuck has a rear holding area that can be mounted inside a collet chuck and a front receiving area for holding a tool shank. A through opening runs from a front face of the receiving area to a rear face of the holding area. A clamping area extends into the rear holding area. Here, the adapter is formed with a plurality of slots, which extend radially outward from the through opening and are distributed over the circumference. The slots are arranged in a central area of the through opening and the front ends of the slots are spaced apart from the front face of the receiving area.