A steering system, comprising: a steering shaft extensible and contractible in a column axis direction; a column jacket including: a lower jacket; and an upper jacket fitted to the lower jacket, the column jacket supporting the steering shaft such that the steering shaft is rotatable and being extensible and contractible in the column axis direction; a first tooth member (60; 60Q; 60R) having a plurality of first teeth (62; 62R) arrayed in the column axis direction and being movable together with the upper jacket; and a receiving member (40; 60Q) provided on one of the upper jacket and the lower jacket and having a receiving surface (44a; 60f); the steering system being characterized by comprising a second tooth member (70; 70Q; 70R) including: a received portion (71; 79a) received by the receiving surface; and second teeth (74; 74R) spaced away from the received portion (71; 79a) and configured to achieve a telescopic lock by meshing with the first teeth (62; 62R), the second tooth member (70; 70Q; 70R) being rotatably supported by a fulcrum (MS; MSQ) that is formed on the receiving surface (44a; 60f) at a contact position between the receiving surface (44a; 60f) and the received portion (71; 79a) and that is movable in the column axis direction; a support member supported by the lower jacket; and a guide mechanism (80; 80P) including: a guide shaft (81; 81P) supported by the support member and extending in a direction orthogonal to the column axis direction; and an elongated hole formed in the second tooth member (70; 70Q; 70R) with the guide shaft (81; 81P) inserted into the elongated hole, the guide mechanism (81; 81P) being configured to guide the second tooth member (70; 70Q; 70R) in a meshing and unmeshing direction. a steering shaft extensible and contractible in a column axis direction; a column jacket including: a lower jacket; and an upper jacket fitted to the lower jacket, the column jacket supporting the steering shaft such that the steering shaft is rotatable and being extensible and contractible in the column axis direction; a lower jacket; and an upper jacket fitted to the lower jacket, the column jacket supporting the steering shaft such that the steering shaft is rotatable and being extensible and contractible in the column axis direction; a first tooth member (60; 60Q; 60R) having a plurality of first teeth (62; 62R) arrayed in the column axis direction and being movable together with the upper jacket; and a receiving member (40; 60Q) provided on one of the upper jacket and the lower jacket and having a receiving surface (44a; 60f); the steering system being characterized by comprising a second tooth member (70; 70Q; 70R) including: a received portion (71; 79a) received by the receiving surface; and second teeth (74; 74R) spaced away from the received portion (71; 79a) and configured to achieve a telescopic lock by meshing with the first teeth (62; 62R), the second tooth member (70; 70Q; 70R) being rotatably supported by a fulcrum (MS; MSQ) that is formed on the receiving surface (44a; 60f) at a contact position between the receiving surface (44a; 60f) and the received portion (71; 79a) and that is movable in the column axis direction; a received portion (71; 79a) received by the receiving surface; and second teeth (74; 74R) spaced away from the received portion (71; 79a) and configured to achieve a telescopic lock by meshing with the first teeth (62; 62R), the second tooth member (70; 70Q; 70R) being rotatably supported by a fulcrum (MS; MSQ) that is formed on the receiving surface (44a; 60f) at a contact position between the receiving surface (44a; 60f) and the received portion (71; 79a) and that is movable in the column axis direction; a support member supported by the lower jacket; and a guide mechanism (80; 80P) including: a guide shaft (81; 81P) supported by the support member and extending in a direction orthogonal to the column axis direction; and an elongated hole formed in the second tooth member (70; 70Q; 70R) with the guide shaft (81; 81P) inserted into the elongated hole, the guide mechanism (81; 81P) being configured to guide the second tooth member (70; 70Q; 70R) in a meshing and unmeshing direction. a guide shaft (81; 81P) supported by the support member and extending in a direction orthogonal to the column axis direction; and an elongated hole formed in the second tooth member (70; 70Q; 70R) with the guide shaft (81; 81P) inserted into the elongated hole, the guide mechanism (81; 81P) being configured to guide the second tooth member (70; 70Q; 70R) in a meshing and unmeshing direction.