A child carrier comprising: a frame; at least one wheel unit including a hub, a plurality of spokes radiating from said hub, and an axle that rotatably extends through said hub; and a brake device including a base unit that is connected to said frame and that is formed with a first guiding groove and a through hole, said axle extending through said base unit and rotatably connecting said wheel unit to said base unit, an operable unit that is pivotally connected to said base unit and that includes at least one side wall formed with a first positioning hole and a second guiding groove, said operable unit being pivotable with respect to said base unit between a brake position and a release position, a brake unit that is disposed in said first and second guiding grooves (43, 54), and that is slidable in said first and second guiding grooves (43, 54) when said operable unit pivots with respect to said base unit between the brake position, where said brake unit is disposed between adjacent two of said spokes, and the release position, where said brake unit is separated from said spokes, and a positioning unit that is disposed in said through hole in said base unit and that includes a positioning component and an elastic member for providing a biasing force to said positioning component, said first positioning hole being registered with said through hole and said positioning component engaging said first positioning hole when said operable unit is at one of the brake position and the release position; said child carrier being characterized in that said brake unit and said positioning unit are separately disposed at said base unit. a frame; at least one wheel unit including a hub, a plurality of spokes radiating from said hub, and an axle that rotatably extends through said hub; and a brake device including a base unit that is connected to said frame and that is formed with a first guiding groove and a through hole, said axle extending through said base unit and rotatably connecting said wheel unit to said base unit, an operable unit that is pivotally connected to said base unit and that includes at least one side wall formed with a first positioning hole and a second guiding groove, said operable unit being pivotable with respect to said base unit between a brake position and a release position, a brake unit that is disposed in said first and second guiding grooves (43, 54), and that is slidable in said first and second guiding grooves (43, 54) when said operable unit pivots with respect to said base unit between the brake position, where said brake unit is disposed between adjacent two of said spokes, and the release position, where said brake unit is separated from said spokes, and a positioning unit that is disposed in said through hole in said base unit and that includes a positioning component and an elastic member for providing a biasing force to said positioning component, said first positioning hole being registered with said through hole and said positioning component engaging said first positioning hole when said operable unit is at one of the brake position and the release position; said child carrier being characterized in that said brake unit and said positioning unit are separately disposed at said base unit. a base unit that is connected to said frame and that is formed with a first guiding groove and a through hole, said axle extending through said base unit and rotatably connecting said wheel unit to said base unit, an operable unit that is pivotally connected to said base unit and that includes at least one side wall formed with a first positioning hole and a second guiding groove, said operable unit being pivotable with respect to said base unit between a brake position and a release position, a brake unit that is disposed in said first and second guiding grooves (43, 54), and that is slidable in said first and second guiding grooves (43, 54) when said operable unit pivots with respect to said base unit between the brake position, where said brake unit is disposed between adjacent two of said spokes, and the release position, where said brake unit is separated from said spokes, and a positioning unit that is disposed in said through hole in said base unit and that includes a positioning component and an elastic member for providing a biasing force to said positioning component, said first positioning hole being registered with said through hole and said positioning component engaging said first positioning hole when said operable unit is at one of the brake position and the release position; said child carrier being characterized in that said brake unit and said positioning unit are separately disposed at said base unit.