A steering device comprising: a steering shaft including a first end to which a steering member is mounted and a second end, wherein the steering shaft is telescopically adjustable in an axial direction of the steering shaft; a column jacket rotatably supporting the steering shaft and including an upper jacket positioned on a first end side and a lower jacket positioned on a second end side, wherein the column jacket is telescopically adjustable together with the steering shaft with movement of the upper jacket relative to the lower jacket in the axial direction; a lock plate fixed to the upper jacket and provided with a plurality of holes arranged in the axial direction and a plurality of partition portions arranged in the axial direction, wherein each of the partition portions is adjacent to the first end side of the corresponding one of the holes; a support bracket fixed to a vehicle body and supporting the column jacket; an operation member supported by the support bracket, wherein the operation member is operated when the steering shaft and the column jacket are telescopically adjusted; and a tooth that advances to and retreats from the lock plate in accordance with operation of the operation member, and that advances to the lock plate to be engaged with one of the holes of the lock plate, characterized in that the partition portions are provided such that a height of a first end-side partition portion in a direction toward the tooth retreated from the lock plate is greater than that of a second end-side partition portion positioned on the second end side of the first end-side partition portion. a steering shaft including a first end to which a steering member is mounted and a second end, wherein the steering shaft is telescopically adjustable in an axial direction of the steering shaft; a column jacket rotatably supporting the steering shaft and including an upper jacket positioned on a first end side and a lower jacket positioned on a second end side, wherein the column jacket is telescopically adjustable together with the steering shaft with movement of the upper jacket relative to the lower jacket in the axial direction; a lock plate fixed to the upper jacket and provided with a plurality of holes arranged in the axial direction and a plurality of partition portions arranged in the axial direction, wherein each of the partition portions is adjacent to the first end side of the corresponding one of the holes; a support bracket fixed to a vehicle body and supporting the column jacket; an operation member supported by the support bracket, wherein the operation member is operated when the steering shaft and the column jacket are telescopically adjusted; and a tooth that advances to and retreats from the lock plate in accordance with operation of the operation member, and that advances to the lock plate to be engaged with one of the holes of the lock plate, characterized in that the partition portions are provided such that a height of a first end-side partition portion in a direction toward the tooth retreated from the lock plate is greater than that of a second end-side partition portion positioned on the second end side of the first end-side partition portion.