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; a support bracket fixed to a vehicle body and supporting the column jacket; a lock member that advances to and retreats from the lock plate between an advance position at which the lock member is engaged with one of the holes of the lock plate and a retreat position at which the lock member is disengaged from the hole of the lock plate; and a biasing member that constantly biases the lock member toward the advance position irrespective of operation of an operation member, characterized by: the operation member supported by the support bracket in a state in which the operation member is mechanically separated from the lock member, wherein the operation member is operated when the steering shaft and the column jacket are telescopically adjusted; and a transmission member (38; 68) that moves the lock member to the retreat position against a biasing force of the biasing member in accordance with the operation of the operation member. 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; a support bracket fixed to a vehicle body and supporting the column jacket; a lock member that advances to and retreats from the lock plate between an advance position at which the lock member is engaged with one of the holes of the lock plate and a retreat position at which the lock member is disengaged from the hole of the lock plate; and a biasing member that constantly biases the lock member toward the advance position irrespective of operation of an operation member, characterized by: the operation member supported by the support bracket in a state in which the operation member is mechanically separated from the lock member, wherein the operation member is operated when the steering shaft and the column jacket are telescopically adjusted; and a transmission member (38; 68) that moves the lock member to the retreat position against a biasing force of the biasing member in accordance with the operation of the operation member. the operation member supported by the support bracket in a state in which the operation member is mechanically separated from the lock member, wherein the operation member is operated when the steering shaft and the column jacket are telescopically adjusted; and a transmission member (38; 68) that moves the lock member to the retreat position against a biasing force of the biasing member in accordance with the operation of the operation member.