This infant chair comprises an independent seat (4) being related to a headrest (5) being fit to be positioned at different heights, the seat thus adopting different in-depth positions, the lifting of the headrest to a higher position bringing about a bigger depth for the seat's position. The seat is formed by an assembly of two plates (6 and 7) being transversally linked to each other in a pin-jointed connection, said assembly being linked in a pin-jointed connection to a lower support (9) being in its turn linked in a pin-jointed connection to a third plate (11), this latter being the one that is related to the headrest (5).