Accordingly, the child can lie on or lean against the backrest 14 comfortably.Referring to FIGS. 6 and 7, FIG. 6 is a schematic diagram illustrating the driving device 34, which is shown in FIG. 4, moving to a releasing position relative to the backrest 14, and FIG. 7 is an enlarged view illustrating the first and secondengaging members 30 and 32, which are shown in FIG. 5, disengaged from the too