A headrest adjustment device includes a linear drive device, a linkage member and an adjustment assembly which includes a fixing member and a headrest bracket. The linkage member is fixed with the headrest bracket and provided with a buffer groove, and the linear drive device has an output rod for linear reciprocating motion. One end of the output rod is connected to one end of the buffer groove, and an angle is formed between the buffer groove and the output rod. The output rod pushes the linkage member to adjust the position and the angle of the headrest, or pulls back the linkage member to fold the headrest. When the headrest is folded, if the hand hinders the headrest movement, the linkage member will move in opposite directions, so that the headrest does not continue to lower which reduces the risk of one's hand injuries.