A steering column apparatus, comprising: a jacket including a cylindrical inner jacket and a cylindrical outer jacket, the cylindrical inner jacket being inserted through an inside of the cylindrical outer jacket; a steering shaft rotatably supported on the jacket, the steering shaft having one end linked to a steering wheel and the other end linked to a steerable gear side; a telescopic adjustment mechanism with an electrically driven motor as a driving source, the telescopic adjustment mechanism being adjustable a forward-or-backward position of the steering wheel by modifying a projection quantity of the cylindrical inner jacket projected from one end side of the cylindrical outer jacket; and the telescopic adjustment mechanism comprises: a supporting unit placed within an rectangular opening hole and fixed to an outer peripheral surface of the inner jacket; and an axle member movably supported on the outer jacket along the axial direction of the jacket and having a tip linked to the supporting unit, characterized in an arc shaped member which is formed by bending a thin plate material, the arc shaped member being interposed between the cylindrical outer jacket and the cylindrical inner jacket; and a biasing mechanism configured to press the outer peripheral surface of the cylindrical inner jacket on an inner peripheral surface of the cylindrical outer jacket via the arc shaped member, wherein the rectangular opening hole having a pair of elongated side sections along an axial direction of the jacket is formed on one end side of the outer jacket, the biasing mechanism comprises a pressing member disposed along the axial direction of the outer jacket at an opposite side of a circumferential direction of the opening hole and biased to project from the inner peripheral surface of the outer jacket toward a radial direction of the outer jacket, and the inner jacket is always biased toward the opening hole side by means of a biasing force of the pressing member and is supported via the arc shaped member at both side sections of the opening hole in the inner peripheral surface of the outer jacket placed along the pair of elongated side sections. a jacket including a cylindrical inner jacket and a cylindrical outer jacket, the cylindrical inner jacket being inserted through an inside of the cylindrical outer jacket; a steering shaft rotatably supported on the jacket, the steering shaft having one end linked to a steering wheel and the other end linked to a steerable gear side; a telescopic adjustment mechanism with an electrically driven motor as a driving source, the telescopic adjustment mechanism being adjustable a forward-or-backward position of the steering wheel by modifying a projection quantity of the cylindrical inner jacket projected from one end side of the cylindrical outer jacket; and the telescopic adjustment mechanism comprises: a supporting unit placed within an rectangular opening hole and fixed to an outer peripheral surface of the inner jacket; and an axle member movably supported on the outer jacket along the axial direction of the jacket and having a tip linked to the supporting unit, characterized in an arc shaped member which is formed by bending a thin plate material, the arc shaped member being interposed between the cylindrical outer jacket and the cylindrical inner jacket; and a biasing mechanism configured to press the outer peripheral surface of the cylindrical inner jacket on an inner peripheral surface of the cylindrical outer jacket via the arc shaped member, wherein the rectangular opening hole having a pair of elongated side sections along an axial direction of the jacket is formed on one end side of the outer jacket, the biasing mechanism comprises a pressing member disposed along the axial direction of the outer jacket at an opposite side of a circumferential direction of the opening hole and biased to project from the inner peripheral surface of the outer jacket toward a radial direction of the outer jacket, and the inner jacket is always biased toward the opening hole side by means of a biasing force of the pressing member and is supported via the arc shaped member at both side sections of the opening hole in the inner peripheral surface of the outer jacket placed along the pair of elongated side sections.