To provide a headrest and its base material on a core-attached stay, offering safety improved by allowing even the stay having a micro-curved surface to stably and efficiently absorb collision energy.

The base material for the headrest comprises: the stay 2 having an upper-end part 20a of a pair of leg portions 20 connected at a connecting portion 21; the core 3 attached to a top portion 2a of the stay 2 with an energy absorption space 6 kept between a front plate portion 30 and the connecting portion; and an energy absorbing structure 5 with a pair of standing plate portions 51 installed in a standing manner while facing a back face 30b of the front plate portion and connected to each other with a top plate portion 52, wherein the energy absorbing structure 5 is disposed in the space 6 in such a manner that a top face 52a of the top plate portion 52 abuts on or is in proximity to the connecting portion 21.