A caster, wherein the caster comprises a bracket , a first transmission device and two wheels , the two wheels are connected by a transmission screw and fixed to the bracket ; and the first transmission device comprises an annular retaining portion and a plurality of first balls , the plurality of first balls are arranged equiangularly in a circumferential direction of the annular retaining portion , characterized in that , the annular retaining portion comprises a first ball washer and a second ball washer , and the first ball washer and the second ball washer are each embedded in the respective wheels ; wherein the caster further comprises a brake device which comprises a brake pin sleeve , a brake screw and a brake block ; the bracket is connected with a shock absorbing portion which is located at the top end of the brake block ; the brake screw is slidably connected to the shock absorbing portion and the brake block is located at the upper portion of the wheels ; the upper portion of the brake screw is sleeved with the brake pin sleeve , and an elastic member is connected between the brake pin sleeve and the shock absorbing portion ; wherein the top of the brake block is provided with two first positioning blocks that are oppositely disposed and two first positioning slots that are oppositely disposed, and inside of the bracket is provided with two second positioning blocks that are oppositely disposed and two second positioning slots that are oppositely disposed; the first positioning blocks are each slidably connected to the respective second positioning slots , and the second positioning blocks are each slidably connected to the respective first positioning slots . the first transmission device comprises an annular retaining portion and a plurality of first balls , the plurality of first balls are arranged equiangularly in a circumferential direction of the annular retaining portion , characterized in that , the annular retaining portion comprises a first ball washer and a second ball washer , and the first ball washer and the second ball washer are each embedded in the respective wheels ; wherein the caster further comprises a brake device which comprises a brake pin sleeve , a brake screw and a brake block ; the bracket is connected with a shock absorbing portion which is located at the top end of the brake block ; the brake screw is slidably connected to the shock absorbing portion and the brake block is located at the upper portion of the wheels ; the upper portion of the brake screw is sleeved with the brake pin sleeve , and an elastic member is connected between the brake pin sleeve and the shock absorbing portion ; wherein the top of the brake block is provided with two first positioning blocks that are oppositely disposed and two first positioning slots that are oppositely disposed, and inside of the bracket is provided with two second positioning blocks that are oppositely disposed and two second positioning slots that are oppositely disposed; the first positioning blocks are each slidably connected to the respective second positioning slots , and the second positioning blocks are each slidably connected to the respective first positioning slots . <EOS>