A head rest that can secure backward view when it is not used, and enable adjustment of its front-and-rear position in use. The head rest is rotatable from a rearmost position to a stored position in which the head rest is tilted down forward. When the head rest is in a use range from the rearmost position to a forward adjustment limit position located in front, the tilting angle of the head rest is adjustable, and the head rest can be rotated forward to the stored position and rotated backward to the rearmost position. By contrast, when the head rest is in the stored position, forward rotation and backward rotation of the head rest are regulated, and the head rest can be rotated backward to the rearmost position.