A medium conveyance route switching device for an automated teller machine, comprising: a support unit located at a branching point of a first conveyance path, a second conveyance path and a third conveyance path where conveyance directions of a medium converge in three directions; a gate assembly including a first gate, a second gate and a third gate positioned on one end of the first conveyance path, the second conveyance path and the third conveyance path, respectively, to guide at the branching point the medium to other conveyance paths among the first conveyance path, the second conveyance path and the third conveyance path than a conveyance path from which the medium is conveyed; and a rotation mechanism configured to rotate the first gate, the second gate and the third gate, wherein the rotation mechanism includes: a first actuator configured to rotate the first gate to switch the medium conveyed from the first conveyance path to the second conveyance path or the third conveyance path; and a second actuator configured to, when the first gate is rotated, rotate the second gate and the third gate together so that the second conveyance path and the third conveyance path become open or close, characterized in that the support unit includes: a first support piece having a first through-hole portion; a second support piece having a second through-hole portion, wherein one side wall of the second support piece remains in contact with one side wall of the first support piece; a third support piece having a third through-hole portion, wherein one side wall of the third support piece remains in contact with another side wall of the second support piece and another side wall of the first support piece; and a fixing shaft configured to extend through the first through-hole portion, the second through-hole portion and the third through-hole portion to fix the first support piece, the second support piece and the third support piece. a support unit located at a branching point of a first conveyance path, a second conveyance path and a third conveyance path where conveyance directions of a medium converge in three directions; a gate assembly including a first gate, a second gate and a third gate positioned on one end of the first conveyance path, the second conveyance path and the third conveyance path, respectively, to guide at the branching point the medium to other conveyance paths among the first conveyance path, the second conveyance path and the third conveyance path than a conveyance path from which the medium is conveyed; and a rotation mechanism configured to rotate the first gate, the second gate and the third gate, wherein the rotation mechanism includes: a first actuator configured to rotate the first gate to switch the medium conveyed from the first conveyance path to the second conveyance path or the third conveyance path; and a second actuator configured to, when the first gate is rotated, rotate the second gate and the third gate together so that the second conveyance path and the third conveyance path become open or close, characterized in that the support unit includes: a first support piece having a first through-hole portion; a second support piece having a second through-hole portion, wherein one side wall of the second support piece remains in contact with one side wall of the first support piece; a third support piece having a third through-hole portion, wherein one side wall of the third support piece remains in contact with another side wall of the second support piece and another side wall of the first support piece; and a fixing shaft configured to extend through the first through-hole portion, the second through-hole portion and the third through-hole portion to fix the first support piece, the second support piece and the third support piece. a first actuator configured to rotate the first gate to switch the medium conveyed from the first conveyance path to the second conveyance path or the third conveyance path; and a second actuator configured to, when the first gate is rotated, rotate the second gate and the third gate together so that the second conveyance path and the third conveyance path become open or close, characterized in that the support unit includes: a first support piece having a first through-hole portion; a second support piece having a second through-hole portion, wherein one side wall of the second support piece remains in contact with one side wall of the first support piece; a third support piece having a third through-hole portion, wherein one side wall of the third support piece remains in contact with another side wall of the second support piece and another side wall of the first support piece; and a fixing shaft configured to extend through the first through-hole portion, the second through-hole portion and the third through-hole portion to fix the first support piece, the second support piece and the third support piece. a first support piece having a first through-hole portion; a second support piece having a second through-hole portion, wherein one side wall of the second support piece remains in contact with one side wall of the first support piece; a third support piece having a third through-hole portion, wherein one side wall of the third support piece remains in contact with another side wall of the second support piece and another side wall of the first support piece; and a fixing shaft configured to extend through the first through-hole portion, the second through-hole portion and the third through-hole portion to fix the first support piece, the second support piece and the third support piece.