To provide a backrest for an automobile seat capable of further adjusting a headrest even by hand.

The backrest for the automobile seat includes the headrest the height of which is adjustable by a guide mechanism and a lateral strut provided on an upper side region of the backrest and fixed and connected to the backrest. The guide mechanism includes a guide device fixedly attached to the lateral strut to guide a guide element and the guide element is attached to the headrest. The backrest assembled to the headrest is characterized in that the guide mechanism (22) is assigned a latching unit (50) including a first latching component (51) fixed to a lateral strut (18) and a second latching component (52) fixed to a headrest (4), and two latching components (51, 52) interact with each other in accordance with a principle of latch and hole.